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Document And Entity Information - shares	3 Months Ended
Document And Entity Information - shares	Mar. 31, 2020	May 01, 2020
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Registrant Name	IGM Biosciences, Inc.
Entity Central Index Key	0001496323
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	IGMS
Security Exchange Name	NASDAQ
Entity File Number	001-39045
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	77-0349194
Entity Address, Address Line One	325 E. Middlefield Road
Entity Address, City or Town	Mountain View
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94043
City Area Code	650
Local Phone Number	965-7873
Document Quarterly Report	true
Document Transition Report	false
Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		24,159,705
Non-voting Common Stock
Document And Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		6,431,205

Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 48,055	$ 35,891
Short-term investments	158,714	188,743
Prepaid expenses and other current assets	5,737	6,431
Income tax receivable		35
Total current assets	212,506	231,100
Property, plant and equipment, net	4,683	3,882
Long-term investments	12,195	11,973
Operating lease right-of-use asset	13,508	14,137
Other assets	258	258
Total assets	243,150	261,350
Current liabilities:
Accounts payable	1,984	3,087
Accrued liabilities	3,031	3,305
Lease liabilities, current	2,529	2,483
Total current liabilities	7,544	8,875
Lease liabilities, non-current	11,595	12,244
Total liabilities	19,139	21,119
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.01 par value; 200,000,000 shares authorized as of March 31, 2020 and December 31, 2019; 0 shares issued and outstanding as of March 31, 2020 and December 31, 2019
Common stock, value	241	240
Additional paid-in-capital	348,330	347,089
Accumulated other comprehensive income	205	43
Accumulated deficit	(124,829)	(107,205)
Total stockholders’ equity	224,011	240,231
Total liabilities and stockholders’ equity	243,150	261,350
Non-voting Common Stock
Stockholders' equity:
Common stock, value	64	64
Total stockholders’ equity	$ 64	$ 64

Condensed Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating expenses:
Research and development	$ 14,583	$ 5,912
General and administrative	3,990	1,445
Total operating expenses	18,573	7,357
Loss from operations	(18,573)	(7,357)
Other income (expense), net	949	(113)
Net loss	$ (17,624)	$ (7,470)
Net loss per share, basic and diluted	$ (0.58)	$ (16.86)
Weighted-average common shares outstanding, basic and diluted	30,491,463	443,118

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Condensed Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Due To (From) Related Party	Convertible Preferred Stock	Non-voting Common Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Convertible preferred stock balance at Dec. 31, 2018			$ 60,917
Convertible preferred stock balance, shares at Dec. 31, 2018			9,501,620
Convertible preferred stock balance at Mar. 31, 2019			$ 60,917
Convertible preferred stock balance, shares at Mar. 31, 2019			9,501,620
Balance at Dec. 31, 2018	$ (65,828)	$ (2,511)			$ 4	$ 751		$ (64,072)
Balance, shares at Dec. 31, 2018					438,074
Exercise of stock options	10					10
Exercise of stock options, shares					7,566
Capital contribution from related party	23					23
Stock-based compensation expense	139					139
Net loss	(7,470)							(7,470)
Balance at Mar. 31, 2019	(73,126)	$ (2,511)			$ 4	923		(71,542)
Balance, shares at Mar. 31, 2019					445,640
Balance at Dec. 31, 2019	240,231			$ 64	$ 240	347,089	$ 43	(107,205)
Balance, shares at Dec. 31, 2019				6,431,205	24,053,921
Exercise of stock options	$ 22				$ 1	21
Exercise of stock options, shares	15,885				15,885
Unrealized gain on investments	$ 162						162
Stock-based compensation expense	1,220					1,220
Net loss	(17,624)							(17,624)
Balance at Mar. 31, 2020	$ 224,011			$ 64	$ 241	$ 348,330	$ 205	$ (124,829)
Balance, shares at Mar. 31, 2020				6,431,205	24,069,806

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (17,624)	$ (7,470)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	222	114
Stock-based compensation expense	1,323	139
Accrued interest on related party loan		125
Net amortization of premiums and accretion of discounts on investments	(306)
Non-cash lease expense	629	180
Changes in assets and liabilities:
Prepaid expenses and other current assets	735	(989)
Income tax receivable	35
Accounts payable	(1,383)	1,821
Accrued liabilities	585	(2,030)
Lease liabilities	(603)	(226)
Other current liabilities		(9)
Net cash used in operating activities	(16,387)	(8,345)
Cash flows from investing activities:
Purchase of property, plant and equipment	(1,705)	(715)
Purchases of investments	(41,131)
Maturities of investments	71,365
Net cash provided by (used in) investing activities	28,529	(715)
Cash flows from financing activities:
Proceeds from exercise of stock options	22	10
Net cash provided by financing activities	22	10,033
Net increase in cash, cash equivalents and restricted cash	12,164	973
Cash, cash equivalents and restricted cash, beginning of period	35,891	1,987
Cash, cash equivalents and restricted cash, end of period	48,055	2,960
Cash, cash equivalents and restricted cash, end of period
Cash and cash equivalents	48,055	2,860
Restricted cash		100
Cash, cash equivalents and restricted cash, end of period	48,055	2,960
Supplemental disclosure of non-cash investing and financing activities:
Acquisition of property, plant and equipment in accounts payable and accrued liabilities	280	18
Series C Convertible Preferred Stock
Supplemental disclosure of non-cash investing and financing activities:
Issuance costs in accounts payable and accrued liabilities	$ 40
Haldor Topsøe Holding A/S and Holdco
Cash flows from financing activities:
Proceeds from related party capital contribution		23
Proceeds from loan from related party		$ 10,000

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Note 2. Summary of Significant Accounting Policies

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company evaluates its estimates, including, but not limited to, those related to investments, manufacturing accruals, accrued research and development expenses, fair value of common stock, stock-based compensation, operating lease right-of-use (ROU) assets and liabilities, income tax uncertainties and the valuation of deferred tax assets. The Company bases its estimates on its historical experience and also on assumptions that it believes are reasonable; however, actual results could significantly differ from those estimates.

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and investments. The Company invests in money market funds, U.S. Treasury securities, U.S. government agency securities, corporate debt and commercial paper. The Company maintains bank deposits in federally insured financial institutions and these deposits may exceed federally insured limits. The Company is exposed to credit risk in the event of a default by the financial institutions holding its cash and issuers of investments to the extent recorded on the condensed balance sheets. The Company’s investment policy limits investments to money market funds, certain types of debt securities issued by the U.S. Government and its agencies, corporate debt, commercial paper, and places restrictions on the credit ratings, maturities and concentration by type and issuer. The Company has not experienced any losses on its deposits of cash and investments.

The Company’s future results of operations involve a number of other risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, the Company’s early stages of clinical drug development; uncertainties related to the use of engineered IgM antibodies, which is a novel and unproven therapeutic approach; the Company’s ability to advance product candidates into, and successfully complete, clinical trials on the timelines it projects; the Company’s ability to adequately demonstrate sufficient safety and efficacy of its product candidates; the Company’s ability to enroll patients in its ongoing and future clinical trials; the Company’s ability to successfully manufacture and supply its product candidates for clinical trials; the Company’s ability to obtain additional capital to finance its operations; uncertainties related to the projections of the size of patient populations suffering from the diseases the Company is targeting; the Company’s ability to obtain, maintain, and protect its intellectual property rights; developments relating to the Company’s competitors and its industry, including competing product candidates and therapies; general economic and market conditions; and other risks and uncertainties, including those more fully described in the “Risk Factors” section of this Quarterly Report on Form 10-Q.

The Company’s product candidates will require approvals from the U.S. Food and Drug Administration and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company.

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash and cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts and are stated at fair value. Restricted cash consisted of a money market account, which was closed during 2019, that served as collateral for a credit card agreement at one of the Company’s financial institutions.

Investments

The Company’s investments have been classified and accounted for as available-for-sale securities. Fixed income securities consist of U.S. Treasury securities, U.S. government agency securities, corporate debt, and commercial paper. The specific identification method is used to determine the cost basis of fixed income securities sold. These securities are recorded on the condensed balance sheets at fair value. Unrealized gains and losses on these securities are included as a separate component of accumulated other comprehensive income. The cost of investment securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in other income (expense), net. Realized gains and losses and declines in fair value judged to be other-than-temporary, if any, are also included in other income (expense), net. The Company evaluates securities for other-than-temporary impairment at the balance sheet date. Declines in fair value determined to be other-than-temporary are also included in other income (expense), net. The Company classifies its investments as short or long term primarily based on the remaining contractual maturity of the securities.

Property, Plant and Equipment

Property, plant and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful economic lives of the related assets.

Upon retirement or sale of the assets, the cost and related accumulated depreciation and amortization are removed from the balance sheet and the resulting gain or loss are recorded to the statement of operations. Repairs and maintenance are charged to operations as incurred.

Research and Development Expenses

The Company expenses research and developments costs as they are incurred. Research and development expenses consist primarily of: (i) personnel-related expenses, including salaries, benefits and stock-based compensation expense, for personnel in the Company’s research and development functions; (ii) fees paid to third parties such as contractors, consultants and contract research organizations (CROs), for conducting clinical trials, animal studies, and other costs related to clinical and preclinical testing; (iii) costs related to acquiring and manufacturing research and clinical trial materials, including under agreements with third parties such as contract manufacturing organizations (CMOs), and other vendors; (iv) costs related to the preparation of regulatory submissions; (v) expenses related to laboratory supplies and services; and (vi) depreciation of equipment and facilities expenses.

Accrued Research and Development Expenses

The Company records accruals for estimated costs of research, preclinical studies, clinical trials, and manufacturing, which are significant components of research and development expenses. A substantial portion of the Company’s ongoing research and development activities is conducted by third-party service providers, CROs and CMOs. The Company’s contracts with CROs generally include pass-through fees such as costs related to animal studies and safety tests, regulatory expenses, investigator fees, travel costs and other miscellaneous costs, including shipping and printing fees. The Company’s contracts with the CMOs generally include fees such as initiation fees, reservation fees, verification run costs, materials and reagents expenses, taxes, etc. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company accrues the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective agreements. The Company determines the estimated costs through discussions with internal personnel and external service providers as to the progress, or stage of completion or actual timeline (start-date and end-date) of the services and the agreed-upon fees to be paid for such services. In the event the Company makes advance payments, the payments are recorded as a prepaid expense and recognized as the services are performed.

As actual costs become known, the Company adjusts its accruals. Although the Company does not expect its estimates to be materially different from amounts actually incurred, such estimates for the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in us reporting amounts that are too high or too low in any particular period. The Company’s accrual is dependent, in part, upon the receipt of timely and accurate reporting from CROs and other third-party vendors. Variations in the assumptions used to estimate accruals including, but not limited to, the number of patients enrolled, the rate of patient enrollment and the actual services performed, may vary from the Company’s estimates, resulting in adjustments to clinical trial expenses in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect its financial condition and results of operations. Through March 31, 2020, there have been no material differences from the Company’s estimated accrued research and development expenses to actual expenses.

Stock-Based Compensation

The Company accounts for stock-based compensation by measuring and recognizing compensation expense for all share-based awards made to employees, non-employees and directors based on estimated grant-date fair values. The Company uses the straight-line method to allocate compensation cost to reporting periods over the requisite service period, which is generally the vesting period, and estimates the fair value of share-based awards to employees and directors using the Black-Scholes option-pricing model. If the service inception date precedes the grant date, the Company accrues for the stock-based compensation based on the fair value at the reporting date. The Company accounts for forfeitures as they occur. The fair value of each purchase under the employee stock purchase plan (ESPP) is estimated at the beginning of the offering period using the Black-Scholes option pricing model and recorded as expense over the service period using the straight-line method.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock (including non-voting common stock) outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented.

Leases

Under Accounting Standard Update (ASU) No. 2016-02, Leases (ASC 842) and its associated amendments, the Company determines if an arrangement is a lease at inception. In addition, the Company determines whether leases meet the classification criteria of a finance or operating lease at the lease commencement date considering: (1) whether the lease transfers ownership of the underlying asset to the lessee at the end of the lease term, (2) whether the lease grants the lessee an option to purchase the underlying asset that the lessee is reasonably certain to exercise, (3) whether the lease term is for a major part of the remaining economic life of the underlying asset, (4) whether the present value of the sum of the lease payments and residual value guaranteed by the lessee equals or exceeds substantially all of the fair value of the underlying asset, and (5) whether the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. As of March 31, 2020, the Company's lease population consisted of real estate. As of March 31, 2020, the Company did not have finance leases.

Operating leases are included in operating lease right-of-use (ROU) assets, lease liabilities, current, and lease liabilities, non-current in the Company’s condensed balance sheet. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date if the rate implicit in the lease is not readily determinable. The Company determines the incremental borrowing rate based on an analysis of corporate bond yields with a credit rating similar to the Company. The determination of the Company’s incremental borrowing rate requires management judgment including the development of a synthetic credit rating and cost of debt as the Company currently does not carry any debt. The Company believes that the estimates used in determining the incremental borrowing rate are reasonable based upon current facts and circumstances. Applying different judgments to the same facts and circumstances could result in the estimated amounts to vary. The operating lease ROU assets also include adjustments for prepayments and accrued lease payments and exclude lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options. Operating lease cost is recognized on a straight-line basis over the expected lease term. Variable lease costs represent payments that are dependent on usage, a rate or index. Variable lease cost primarily relates to common area maintenance charges. Lease agreements that include lease and non-lease components are accounted for as a single lease component. Lease agreements with a noncancelable term of less than 12 months are not recorded on the Company’s condensed balance sheet.

Recently Adopted Accounting Standards

In August 2018, the FASB issued ASU No. 2018-13, Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which amends ASC 820, Fair Value Measurement. This ASU modifies the disclosure requirements for fair value measurements by removing, modifying, or adding certain disclosures. The effective date is the first quarter of fiscal year 2020, with early adoption permitted for the removed disclosures and delayed adoption until fiscal year 2020 permitted for the new disclosures. The removed and modified disclosures will be adopted on a retrospective basis and the new disclosures will be adopted on a prospective basis. The Company adopted this ASU as of January 1, 2020 and the adoption did not have a material impact on its financial statements and related disclosures.

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires that financial assets measured at amortized cost be presented at the net amount expected to be collected. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect collectability. This ASU also eliminates the concept of “other-than-temporary” impairment when evaluating available-for-sale debt securities and instead focuses on determining whether any impairment is a result of a credit loss or other factors. An entity will recognize an allowance for credit losses on available-for-sale debt securities rather than an other-than-temporary impairment that reduces the cost basis of the investment. This ASU is effective for fiscal years beginning after December 15, 2022 and interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing the impact of this standard on its financial statements and related disclosures.

In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. The new standard will be effective beginning January 1, 2021. The Company is currently assessing the impact of this standard on its financial statements and related disclosures.

Fair Value Measurement

3 Months Ended

Mar. 31, 2020

Fair Value Disclosures [Abstract]

Fair Value Measurement

Note 3. Fair Value Measurement

The Company applies fair value accounting for all financial assets and liabilities and non-financial assets and liabilities that are recognized or disclosed at fair value in the financial statements on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows:

Level 1—Observable inputs, such as quoted prices in active markets for identical assets or liabilities at the measurement date.

Level 2—Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

Level 3—Unobservable inputs which reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model.

In determining fair value, the Company utilizes valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs to the extent possible as well as considers counterparty credit risk in its assessment of fair value.

Financial instruments classified within Level 2 of the fair value hierarchy are valued based on other observable inputs, including broker or dealer quotations or alternative pricing sources. When quoted prices in active markets for identical assets or liabilities are not available, the Company relies on non-binding quotes from its investment managers, which are based on proprietary valuation models of independent pricing services. These models generally use inputs such as observable market data, quoted market prices for similar instruments, or historical pricing trends of a security relative to its peers. To validate the fair value determination provided by its investment managers, the Company reviews the pricing movement in the context of overall market trends and trading information from its investment managers. In addition, the Company assesses the inputs and methods used in determining the fair value in order to determine the classification of securities in the fair value hierarchy.

The following tables set forth the fair value of the Company’s financial assets, which consist of investments measured and recognized at fair value (in thousands):

		March 31, 2020
	Fair Value Hierarchy Level	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Investments
U.S. Treasury securities	Level 1	$	45,242	$	227	$	—		$	45,469
Corporate bonds	Level 2		40,685		—		(107	)		40,578
Commercial paper	Level 2		63,606		1		—			63,607
U.S. government agency securities	Level 2		21,171		84		—			21,255
Total		$	170,704	$	312	$	(107	)	$	170,909

		December 31, 2019
	Fair Value Hierarchy Level	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Investments
U.S. Treasury securities	Level 1	$	66,244	$	48	$	—		$	66,292
Corporate bonds	Level 2		39,953		3		—			39,956
Commercial paper	Level 2		74,507		—		(9	)		74,498
U.S. government agency securities	Level 2		19,969		1		—			19,970
Total		$	200,673	$	52	$	(9	)	$	200,716

The following table presents the contractual maturities of the Company’s investments as of March 31, 2020 and December 31, 2019 (in thousands):

	March 31,		December 31,
	2020		2019
Due in less than one year	$	158,714	$	188,743
Due in more than one year		12,195		11,973
Total	$	170,909	$	200,716

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Balance Sheet Components

3 Months Ended

Mar. 31, 2020

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

Note 4. Balance Sheet Components

Property, Plant and Equipment, Net

Property, plant and equipment, net consists of the following (in thousands):

	March 31,			December 31,
	2020			2019
Laboratory equipment	$	4,796		$	3,800
Office equipment		150			150
Leasehold improvements		90			78
Construction in progress		1,133			1,118
Total property, plant and equipment, gross		6,169			5,146
Less: Accumulated depreciation		(1,486	)		(1,264	)
Total property, plant and equipment, net	$	4,683		$	3,882

Depreciation expense was approximately $0.2 million and $0.1 million for the three months ended March 31, 2020 and 2019, respectively.

Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	March 31,		December 31,
	2020		2019
Accrued research and development materials and services	$	1,194	$	906
Accrued professional services		437		360
Accrued compensation		1,391		2,030
Other		9		9
Total accrued liabilities	$	3,031	$	3,305

Stock-Based Compensation

3 Months Ended

Mar. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

Note 6. Stock-Based Compensation

2018 Omnibus Incentive Plan (as Amended and Restated)

The Company’s Board of Directors adopted and the Company’s stockholders approved, effective on the day prior to the effectiveness of the registration statement on Form S-1 related to the IPO, an amendment and restatement of the 2018 Omnibus Incentive Plan (the 2018 Plan) which provides for the grant of incentive stock options, within the meaning of Section 422 of the Code to employees, and for the grant of nonstatutory stock options, restricted stock, restricted stock units (RSUs), stock appreciation rights, performance units, and performance shares to employees, directors, and consultants of the Company.

Options granted under the 2018 Plan expire no later than 10 years from the date of grant. The exercise price of options granted under the 2018 Plan must at least be equal to the fair market value of the Company’s common stock on the date of grant. With respect to any participant who owns more than 10% of the voting power of all classes of the Company’s outstanding stock, the term of an incentive stock option granted to such participant must not exceed five years and the exercise price must equal at least 110% of the fair market value on the grant date. Employee stock options generally vest 25% upon one year of continued service to the Company, with the remainder in monthly increments over three additional years.

Subject to an annual evergreen increase and adjustment in the case of certain capitalization events, the Company initially reserved 4,384,000 shares of the Company’s common stock for issuance pursuant to awards under the 2018 Plan. The 2018 Plan is administered by the Compensation Committee of the Company’s Board of Directors. The number of shares of the Company’s common stock available for issuance under the 2018 Plan will also include an annual increase on the first day of each fiscal year beginning with the 2020 fiscal year, equal to the least of (i) 8,768,800 shares, (ii) 4% of the Company’s common stock outstanding at December 31 of the immediately preceding year, or (iii) such number of shares as determined by the Company’s Board of Directors. Effective January 1, 2020, the number of shares of common stock available under the 2018 Plan increased by 964,487 shares pursuant to the evergreen provision of the 2018 Plan. As of March 31, 2020, 2,967,576 shares of common stock remained available for issuance under the 2018 Plan.

2010 Stock Plan (as Amended and Restated)

The 2010 Stock Plan (the 2010 Plan) was originally adopted by the Company’s Board of Directors and approved by the Company’s stockholders in November 2010. The 2010 Plan was amended and restated in December 2017 and April 2019. The 2010 Plan allowed the Company to provide incentive stock options, within the meaning of Section 422 of the Code, nonstatutory stock options and stock purchase rights to eligible employees, consultants and directors and any parent or subsidiary of the Company. The 2010 Plan was terminated in 2019 and the Company will not grant any additional awards under the 2010 Plan. However, the 2010 Plan will continue to govern the terms and conditions of the outstanding awards previously granted under the 2010 Plan.

2019 Employee Stock Purchase Plan

The Company’s Board of Directors adopted and the Company’s stockholders approved, effective on the day prior to the effectiveness of the registration statement on Form S-1 related to the IPO, the 2019 Employee Stock Purchase Plan (ESPP). However, no offering period or purchase period under the ESPP will begin unless and until determined by the Company’s Board of Directors. The ESPP is intended to have two components: a component that is intended to qualify as an “employee stock purchase plan” under Section 423 of the Code (the 423 Component) and a component that is not intended to qualify (the Non-423 Component). The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation. At the end of each offering period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock at the beginning of the offering period or at the end of each applicable purchase period.

Subject to adjustment in the case of certain capitalization events, a total of 280,000 common shares of the Company were available for purchase at adoption of the ESPP. Pursuant to the ESPP, the annual share increase pursuant to the evergreen provision is determined based on the least of (i) 560,000 shares, (ii) 1% of the Company’s common stock outstanding at December 31 of the immediately preceding year, or (iii) such number of shares as determined by the Company’s Board of Directors. Effective January 1, 2020, the number of shares of common stock available under the ESPP increased by 241,121 shares pursuant to the evergreen provision of the ESPP. As of March 31, 2020, 521,121 shares of common stock remained available for issuance under the ESPP.

Stock-Based Compensation Expense

Total stock-based compensation expense recorded related to the 2010 Plan, 2018 Plan, and ESPP was recorded in the condensed statements of operations and allocated as follows (in thousands):

	Three Months Ended
	March 31,
	2020		2019
Research and development	$	666	$	105
General and administrative		657		34
Total stock-based compensation expense	$	1,323	$	139

Accrued stock-based compensation expense for awards where the service inception date precedes grant date was $0.1 million and $0, for the three months ended March 31, 2020 and 2019, respectively.

Stock Options

The following table summarizes stock option activity:

				Outstanding Options
	Shares Available for Grant			Shares			Weighted- Average Exercise		Weighted- Average Remaining Contractual Term (Years)
Balance—December 31, 2019		2,669,264			2,289,209		$	3.36		8.1
Addition - Option pool		964,487
Granted		(679,575	)		679,575		$	39.93
Exercised		—			(15,885	)	$	1.32
Cancelled		13,400			(13,400	)	$	20.02
Balance—March 31, 2020		2,967,576			2,939,499		$	11.75		8.3
Exercisable – March 31, 2020					1,118,904		$	1.77		6.6

The fair value of employee stock options was estimated using the following weighted-average assumptions:

	Three Months Ended
	March 31,
	2020			2019
Expected term in years		6.0			6.0
Expected volatility		83.4	%		79.3	%
Risk-free interest rate		1.2	%		2.5	%
Dividend yield		—			—
Weighted average fair value of share-based awards granted	$	28.1		$	1.0

The fair value of ESPP was estimated using the following weighted-average assumptions:

	Three Months Ended
	March 31,
	2020			2019
Expected term in years		0.7			—
Expected volatility		74.3	%		—
Risk-free interest rate		1.9	%		—
Dividend yield		—			—

Restricted Stock

During December 2018, the Company issued 116,518 shares of common stock to an executive officer under a restricted stock agreement at a grant date fair value of $1.39 per share that vests over two years. Any unvested shares are subject to forfeiture in the case that the grantee’s service terminates. As of March 31, 2020, 58,259 shares of restricted stock were vested. For the three months ended March 31, 2020, the related stock-based compensation was immaterial. As of March 31, 2020, there was $24,000 of unrecognized stock-based compensation related to restricted stock, which the Company expects to recognize over a remaining weighted-average period of 0.3 years.

Net Loss Per Share Attributable to Common Stockholders

3 Months Ended

Mar. 31, 2020

Earnings Per Share [Abstract]

Net Loss Per Share Attributable to Common Stockholders

Note 7. Net Loss Per Share Attributable to Common Stockholders

The following table sets forth the computation of the basic and diluted net loss per share (in thousands except share and per share data):

	Three Months Ended
	March 31,
	2020			2019
Numerator:
Net loss	$	(17,624	)	$	(7,470	)
Denominator:
Weighted average common shares outstanding used to compute net loss per share, basic and diluted		30,491,463			443,118
Net loss per share attributable to common stockholders	$	(0.58	)	$	(16.86	)

Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods as the inclusion of all common stock equivalents outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:

	March 31,
	2020		2019
Series A convertible preferred stock		—		401,004
Series B convertible preferred stock		—		9,100,616
Restricted stock		58,259		116,518
Stock options		2,939,499		2,102,514
Total		2,997,758		11,720,652

Commitments and Contingencies

3 Months Ended

Mar. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

Note 8. Commitments and Contingencies

Operating Leases

The Company leases its headquarters with its main offices and laboratory facilities in Mountain View, California under two lease agreements that end in September 2024 and April 2025.

Information related to the Company’s ROU assets and related lease liabilities were as follows (in thousands except for remaining lease term and discount rate):

	Three Months Ended
	March 31,
	2020		2019
Cash paid for operating lease liabilities	$	740	$	216
Operating lease cost		767		171
Variable lease cost		46		—

	March 31, 2020			December 31, 2019
Current operating lease liabilities	$	2,529		$	2,483
Non-current operating lease liabilities		11,595			12,244
Weighted average remaining lease term in years		5.0			5.1
Weighted average discount rate		3.8	%		3.8	%

Maturities of lease liabilities as of March 31, 2020 were as follows (in thousands):

	Operating
	Lease
Year Ending December	Commitments
2020 (remaining nine months)	$	2,261
2021		3,086
2022		3,172
2023		3,261
2024		3,008
Thereafter		733
Total		15,521
Less imputed interest		(1,397	)
Total lease liabilities	$	14,124

Legal Proceedings

The Company, from time to time, may be party to litigation arising in the ordinary course of business. The Company was not subject to any material legal proceedings during the three months ended March 31, 2020 and, to the best of its knowledge, no material legal proceedings are currently pending or threatened.

Indemnification

The Company enters into standard indemnification arrangements in the ordinary course of business. Pursuant to these arrangements, the Company indemnifies, holds harmless and agrees to reimburse the indemnified parties for losses suffered or incurred by the indemnified party, in connection with any trade secret, copyright, patent or other intellectual property infringement claim by any third party with respect to its technology. The term of these indemnification agreements is generally perpetual any time after the execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these arrangements is not determinable. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. As a result, the Company believes the fair value of these agreements is not material.

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2020
Accounting Policies [Abstract]
Description of the Business	Description of the Business IGM Biosciences, Inc. (the Company) was incorporated in the state of Delaware in August 1993 under the name Palingen, Inc. and the name was subsequently changed to IGM Biosciences, Inc. in 2010. The Company’s headquarters are in Mountain View, California. IGM Biosciences, Inc. is a biotechnology company engaged in the development of IgM antibody therapeutics for the treatment of cancer. In December 2017, the Company established a holding company (Holdco); in April 2019, Holdco was subsequently dissolved and equity interests in Holdco were converted into equity interests in the Company. The information included in these financial statements is consistently presented as if it is that of the Company, even during the interim period when investors held their equity interests in Holdco. Haldor Topsøe Holding A/S is a significant investor in the Company either through its direct equity ownership or indirectly as the majority owner of Holdco, until Holdco was dissolved in April 2019. Haldor Topsøe Holding A/S and Holdco represent a combined entity (Significant Investor) as referenced herein.
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with generally accepted accounting principles in the United States of America (GAAP) and applicable rules and regulations of the Securities and Exchange Commission (SEC) regarding interim financial reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP have been condensed or omitted, and accordingly the balance sheet as of December 31, 2019 has been derived from the audited financial statements at that date but does not include all of the information required by GAAP for complete financial statements. These unaudited interim condensed financial statements have been prepared on the same basis as the Company’s annual financial statements and, in the opinion of management, reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Company’s financial information. The results of operations for the three months ended March 31, 2020 are not necessarily indicative of the results to be expected for the year ending December 31, 2020 or for any other interim period or for any other future year. The accompanying interim unaudited condensed financial statements should be read in conjunction with the audited financial statements and the related notes thereto for the year ended December 31, 2019, included in the Company’s Annual Report on Form 10-K filed with the SEC on March 26, 2020.
Reverse Stock Split	Reverse Stock Split In August 2019, the Company filed an amendment to the Company’s amended and restated certificate of incorporation to effect a reverse split of shares of the Company’s common stock, non-voting common stock and convertible preferred stock, each on a 6.6084–for-1 (Reverse Stock Split). The Reverse Stock Split also applied to any outstanding securities or rights convertible into, or exchangeable or exercisable for, common stock, non-voting common stock or convertible preferred stock. The par value of the common stock was not adjusted as a result of the Reverse Stock Split. All references to common stock, non-voting common stock, restricted stock, options to purchase common stock, share data, per share data, convertible preferred stock and related information contained in the condensed financial statements and related footnotes have been retrospectively adjusted to reflect the effect of the Reverse Stock Split for all periods presented. The Reverse Stock Split was effected on August 30, 2019.
Initial Public Offering	Initial Public Offering On September 17, 2019, the Company’s registration statement on Form S-1 (File No. 333-233365) relating to its initial public offering (IPO) of common stock became effective. The IPO closed on September 20, 2019 at which time the Company issued an aggregate of 12,578,125 shares of its common stock at a price of $16.00 per share, including 1,640,625 shares issued in connection with the full exercise by the underwriters of their option to purchase additional shares of common stock. In addition, immediately prior to the closing of the IPO, all outstanding shares of the Company’s convertible preferred stock automatically converted into 10,787,861 shares of common stock and 6,431,205 shares of non-voting common stock. Proceeds from the IPO, net of underwriting discounts and commissions and offering costs were approximately $183.0 million.
Liquidity	Liquidity The Company has incurred net operating losses and negative cash flows from operations since its inception and had an accumulated deficit of $124.8 million at March 31, 2020. As of March 31, 2020, the Company had cash and investments of $219.0 million. The Company has historically financed its operations primarily through the sale of convertible preferred stock and common stock and the issuance of unsecured promissory notes. To date, none of the Company’s product candidates have been approved for sale, and the Company has not generated any revenue since inception. Management expects operating losses to continue and increase for the foreseeable future, as the Company progresses into clinical development activities for its lead product candidates. The Company’s prospects are subject to risks, expenses and uncertainties frequently encountered by companies in the biotechnology industry as discussed below. While the Company has been able to raise multiple rounds of financing, there can be no assurance that in the event the Company requires additional financing, such financing will be available on terms which are favorable or at all. Failure to generate sufficient cash flows from operations, raise additional capital or reduce certain discretionary spending would have a material adverse effect on the Company’s ability to achieve its intended business objectives.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company evaluates its estimates, including, but not limited to, those related to investments, manufacturing accruals, accrued research and development expenses, fair value of common stock, stock-based compensation, operating lease right-of-use (ROU) assets and liabilities, income tax uncertainties and the valuation of deferred tax assets. The Company bases its estimates on its historical experience and also on assumptions that it believes are reasonable; however, actual results could significantly differ from those estimates.
Concentration of Credit Risk and Other Risks and Uncertainties	Concentration of Credit Risk and Other Risks and Uncertainties Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and investments. The Company invests in money market funds, U.S. Treasury securities, U.S. government agency securities, corporate debt and commercial paper. The Company maintains bank deposits in federally insured financial institutions and these deposits may exceed federally insured limits. The Company is exposed to credit risk in the event of a default by the financial institutions holding its cash and issuers of investments to the extent recorded on the condensed balance sheets. The Company’s investment policy limits investments to money market funds, certain types of debt securities issued by the U.S. Government and its agencies, corporate debt, commercial paper, and places restrictions on the credit ratings, maturities and concentration by type and issuer. The Company has not experienced any losses on its deposits of cash and investments. The Company’s future results of operations involve a number of other risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, the Company’s early stages of clinical drug development; uncertainties related to the use of engineered IgM antibodies, which is a novel and unproven therapeutic approach; the Company’s ability to advance product candidates into, and successfully complete, clinical trials on the timelines it projects; the Company’s ability to adequately demonstrate sufficient safety and efficacy of its product candidates; the Company’s ability to enroll patients in its ongoing and future clinical trials; the Company’s ability to successfully manufacture and supply its product candidates for clinical trials; the Company’s ability to obtain additional capital to finance its operations; uncertainties related to the projections of the size of patient populations suffering from the diseases the Company is targeting; the Company’s ability to obtain, maintain, and protect its intellectual property rights; developments relating to the Company’s competitors and its industry, including competing product candidates and therapies; general economic and market conditions; and other risks and uncertainties, including those more fully described in the “Risk Factors” section of this Quarterly Report on Form 10-Q. The Company’s product candidates will require approvals from the U.S. Food and Drug Administration and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company.
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash and cash equivalents. Cash equivalents consist primarily of amounts invested in money market accounts and are stated at fair value. Restricted cash consisted of a money market account, which was closed during 2019, that served as collateral for a credit card agreement at one of the Company’s financial institutions.
Investments	Investments The Company’s investments have been classified and accounted for as available-for-sale securities. Fixed income securities consist of U.S. Treasury securities, U.S. government agency securities, corporate debt, and commercial paper. The specific identification method is used to determine the cost basis of fixed income securities sold. These securities are recorded on the condensed balance sheets at fair value. Unrealized gains and losses on these securities are included as a separate component of accumulated other comprehensive income. The cost of investment securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion are included in other income (expense), net. Realized gains and losses and declines in fair value judged to be other-than-temporary, if any, are also included in other income (expense), net. The Company evaluates securities for other-than-temporary impairment at the balance sheet date. Declines in fair value determined to be other-than-temporary are also included in other income (expense), net. The Company classifies its investments as short or long term primarily based on the remaining contractual maturity of the securities.
Property, Plant and Equipment	Property, Plant and Equipment Property, plant and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is determined using the straight-line method over the estimated useful lives of the respective assets, generally three to five years. Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or the estimated useful economic lives of the related assets. Upon retirement or sale of the assets, the cost and related accumulated depreciation and amortization are removed from the balance sheet and the resulting gain or loss are recorded to the statement of operations. Repairs and maintenance are charged to operations as incurred.
Research and Development Expenses	Research and Development Expenses The Company expenses research and developments costs as they are incurred. Research and development expenses consist primarily of: (i) personnel-related expenses, including salaries, benefits and stock-based compensation expense, for personnel in the Company’s research and development functions; (ii) fees paid to third parties such as contractors, consultants and contract research organizations (CROs), for conducting clinical trials, animal studies, and other costs related to clinical and preclinical testing; (iii) costs related to acquiring and manufacturing research and clinical trial materials, including under agreements with third parties such as contract manufacturing organizations (CMOs), and other vendors; (iv) costs related to the preparation of regulatory submissions; (v) expenses related to laboratory supplies and services; and (vi) depreciation of equipment and facilities expenses.
Accrued Research and Development Expenses	Accrued Research and Development Expenses The Company records accruals for estimated costs of research, preclinical studies, clinical trials, and manufacturing, which are significant components of research and development expenses. A substantial portion of the Company’s ongoing research and development activities is conducted by third-party service providers, CROs and CMOs. The Company’s contracts with CROs generally include pass-through fees such as costs related to animal studies and safety tests, regulatory expenses, investigator fees, travel costs and other miscellaneous costs, including shipping and printing fees. The Company’s contracts with the CMOs generally include fees such as initiation fees, reservation fees, verification run costs, materials and reagents expenses, taxes, etc. The financial terms of these contracts are subject to negotiations, which vary from contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company accrues the costs incurred under agreements with these third parties based on estimates of actual work completed in accordance with the respective agreements. The Company determines the estimated costs through discussions with internal personnel and external service providers as to the progress, or stage of completion or actual timeline (start-date and end-date) of the services and the agreed-upon fees to be paid for such services. In the event the Company makes advance payments, the payments are recorded as a prepaid expense and recognized as the services are performed. As actual costs become known, the Company adjusts its accruals. Although the Company does not expect its estimates to be materially different from amounts actually incurred, such estimates for the status and timing of services performed relative to the actual status and timing of services performed may vary and could result in us reporting amounts that are too high or too low in any particular period. The Company’s accrual is dependent, in part, upon the receipt of timely and accurate reporting from CROs and other third-party vendors. Variations in the assumptions used to estimate accruals including, but not limited to, the number of patients enrolled, the rate of patient enrollment and the actual services performed, may vary from the Company’s estimates, resulting in adjustments to clinical trial expenses in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect its financial condition and results of operations. Through March 31, 2020, there have been no material differences from the Company’s estimated accrued research and development expenses to actual expenses.
Stock-Based Compensation	Stock-Based Compensation The Company accounts for stock-based compensation by measuring and recognizing compensation expense for all share-based awards made to employees, non-employees and directors based on estimated grant-date fair values. The Company uses the straight-line method to allocate compensation cost to reporting periods over the requisite service period, which is generally the vesting period, and estimates the fair value of share-based awards to employees and directors using the Black-Scholes option-pricing model. If the service inception date precedes the grant date, the Company accrues for the stock-based compensation based on the fair value at the reporting date. The Company accounts for forfeitures as they occur. The fair value of each purchase under the employee stock purchase plan (ESPP) is estimated at the beginning of the offering period using the Black-Scholes option pricing model and recorded as expense over the service period using the straight-line method.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted-average number of shares of common stock (including non-voting common stock) outstanding during the period, without consideration for common stock equivalents. Diluted net loss per share is the same as basic net loss per share, since the effects of potentially dilutive securities are antidilutive given the net loss for each period presented.
Leases	Leases Under Accounting Standard Update (ASU) No. 2016-02, Leases (ASC 842) and its associated amendments, the Company determines if an arrangement is a lease at inception. In addition, the Company determines whether leases meet the classification criteria of a finance or operating lease at the lease commencement date considering: (1) whether the lease transfers ownership of the underlying asset to the lessee at the end of the lease term, (2) whether the lease grants the lessee an option to purchase the underlying asset that the lessee is reasonably certain to exercise, (3) whether the lease term is for a major part of the remaining economic life of the underlying asset, (4) whether the present value of the sum of the lease payments and residual value guaranteed by the lessee equals or exceeds substantially all of the fair value of the underlying asset, and (5) whether the underlying asset is of such a specialized nature that it is expected to have no alternative use to the lessor at the end of the lease term. As of March 31, 2020, the Company's lease population consisted of real estate. As of March 31, 2020, the Company did not have finance leases. Operating leases are included in operating lease right-of-use (ROU) assets, lease liabilities, current, and lease liabilities, non-current in the Company’s condensed balance sheet. ROU assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent the Company’s obligation to make lease payments arising from the lease. Operating lease ROU assets and liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. In determining the present value of lease payments, the Company uses its incremental borrowing rate based on the information available at the lease commencement date if the rate implicit in the lease is not readily determinable. The Company determines the incremental borrowing rate based on an analysis of corporate bond yields with a credit rating similar to the Company. The determination of the Company’s incremental borrowing rate requires management judgment including the development of a synthetic credit rating and cost of debt as the Company currently does not carry any debt. The Company believes that the estimates used in determining the incremental borrowing rate are reasonable based upon current facts and circumstances. Applying different judgments to the same facts and circumstances could result in the estimated amounts to vary. The operating lease ROU assets also include adjustments for prepayments and accrued lease payments and exclude lease incentives. The Company’s lease terms may include options to extend or terminate the lease when it is reasonably certain that the Company will exercise such options. Operating lease cost is recognized on a straight-line basis over the expected lease term. Variable lease costs represent payments that are dependent on usage, a rate or index. Variable lease cost primarily relates to common area maintenance charges. Lease agreements that include lease and non-lease components are accounted for as a single lease component. Lease agreements with a noncancelable term of less than 12 months are not recorded on the Company’s condensed balance sheet.
Recently Adopted Accounting Standards and Accounting Pronouncements	Recently Adopted Accounting Standards In August 2018, the FASB issued ASU No. 2018-13, Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which amends ASC 820, Fair Value Measurement. This ASU modifies the disclosure requirements for fair value measurements by removing, modifying, or adding certain disclosures. The effective date is the first quarter of fiscal year 2020, with early adoption permitted for the removed disclosures and delayed adoption until fiscal year 2020 permitted for the new disclosures. The removed and modified disclosures will be adopted on a retrospective basis and the new disclosures will be adopted on a prospective basis. The Company adopted this ASU as of January 1, 2020 and the adoption did not have a material impact on its financial statements and related disclosures. Recently Issued Accounting Pronouncements In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires that financial assets measured at amortized cost be presented at the net amount expected to be collected. The measurement of expected credit losses is based on historical experience, current conditions, and reasonable and supportable forecasts that affect collectability. This ASU also eliminates the concept of “other-than-temporary” impairment when evaluating available-for-sale debt securities and instead focuses on determining whether any impairment is a result of a credit loss or other factors. An entity will recognize an allowance for credit losses on available-for-sale debt securities rather than an other-than-temporary impairment that reduces the cost basis of the investment. This ASU is effective for fiscal years beginning after December 15, 2022 and interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing the impact of this standard on its financial statements and related disclosures. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (ASU 2019-12), which is intended to simplify the accounting for income taxes. ASU 2019-12 removes certain exceptions to the general principles in Topic 740 and also clarifies and amends existing guidance to improve consistent application. The new standard will be effective beginning January 1, 2021. The Company is currently assessing the impact of this standard on its financial statements and related disclosures.

Fair Value Measurement (Tables)

3 Months Ended

Mar. 31, 2020

Fair Value Disclosures [Abstract]

Summary of Investments Measured and Recognized at Fair Value

The following tables set forth the fair value of the Company’s financial assets, which consist of investments measured and recognized at fair value (in thousands):

		March 31, 2020
	Fair Value Hierarchy Level	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Investments
U.S. Treasury securities	Level 1	$	45,242	$	227	$	—		$	45,469
Corporate bonds	Level 2		40,685		—		(107	)		40,578
Commercial paper	Level 2		63,606		1		—			63,607
U.S. government agency securities	Level 2		21,171		84		—			21,255
Total		$	170,704	$	312	$	(107	)	$	170,909

		December 31, 2019
	Fair Value Hierarchy Level	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Investments
U.S. Treasury securities	Level 1	$	66,244	$	48	$	—		$	66,292
Corporate bonds	Level 2		39,953		3		—			39,956
Commercial paper	Level 2		74,507		—		(9	)		74,498
U.S. government agency securities	Level 2		19,969		1		—			19,970
Total		$	200,673	$	52	$	(9	)	$	200,716

Summary of Contractual Maturities of Investments

The following table presents the contractual maturities of the Company’s investments as of March 31, 2020 and December 31, 2019 (in thousands):

	March 31,		December 31,
	2020		2019
Due in less than one year	$	158,714	$	188,743
Due in more than one year		12,195		11,973
Total	$	170,909	$	200,716

Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2020

Balance Sheet Related Disclosures [Abstract]

Schedule of Property, Plant and Equipment, Net

Property, plant and equipment, net consists of the following (in thousands):

	March 31,			December 31,
	2020			2019
Laboratory equipment	$	4,796		$	3,800
Office equipment		150			150
Leasehold improvements		90			78
Construction in progress		1,133			1,118
Total property, plant and equipment, gross		6,169			5,146
Less: Accumulated depreciation		(1,486	)		(1,264	)
Total property, plant and equipment, net	$	4,683		$	3,882

Schedule of Accrued Liabilities

Accrued liabilities consisted of the following (in thousands):

	March 31,		December 31,
	2020		2019
Accrued research and development materials and services	$	1,194	$	906
Accrued professional services		437		360
Accrued compensation		1,391		2,030
Other		9		9
Total accrued liabilities	$	3,031	$	3,305

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock-Based Compensation Expense

Total stock-based compensation expense recorded related to the 2010 Plan, 2018 Plan, and ESPP was recorded in the condensed statements of operations and allocated as follows (in thousands):

	Three Months Ended
	March 31,
	2020		2019
Research and development	$	666	$	105
General and administrative		657		34
Total stock-based compensation expense	$	1,323	$	139

Summary of Stock Option

The following table summarizes stock option activity:

				Outstanding Options
	Shares Available for Grant			Shares			Weighted- Average Exercise		Weighted- Average Remaining Contractual Term (Years)
Balance—December 31, 2019		2,669,264			2,289,209		$	3.36		8.1
Addition - Option pool		964,487
Granted		(679,575	)		679,575		$	39.93
Exercised		—			(15,885	)	$	1.32
Cancelled		13,400			(13,400	)	$	20.02
Balance—March 31, 2020		2,967,576			2,939,499		$	11.75		8.3
Exercisable – March 31, 2020					1,118,904		$	1.77		6.6

Summary of Fair Value of Employee Stock Options Estimated Weighted-average Assumptions

The fair value of employee stock options was estimated using the following weighted-average assumptions:

	Three Months Ended
	March 31,
	2020			2019
Expected term in years		6.0			6.0
Expected volatility		83.4	%		79.3	%
Risk-free interest rate		1.2	%		2.5	%
Dividend yield		—			—
Weighted average fair value of share-based awards granted	$	28.1		$	1.0

Summary of Fair Value of Employee Stock Purchase Plan Estimated Weighted-average Assumptions

The fair value of ESPP was estimated using the following weighted-average assumptions:

	Three Months Ended
	March 31,
	2020			2019
Expected term in years		0.7			—
Expected volatility		74.3	%		—
Risk-free interest rate		1.9	%		—
Dividend yield		—			—

Net Loss Per Share Attributable to Common Stockholders (Tables)

3 Months Ended

Mar. 31, 2020

Earnings Per Share [Abstract]

Schedule of Computation of Basic and Diluted Net Loss Per Share

The following table sets forth the computation of the basic and diluted net loss per share (in thousands except share and per share data):

	Three Months Ended
	March 31,
	2020			2019
Numerator:
Net loss	$	(17,624	)	$	(7,470	)
Denominator:
Weighted average common shares outstanding used to compute net loss per share, basic and diluted		30,491,463			443,118
Net loss per share attributable to common stockholders	$	(0.58	)	$	(16.86	)

Summary of Potentially Dilutive Securities Not Included in the Diluted Per Share Calculations

Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:

	March 31,
	2020		2019
Series A convertible preferred stock		—		401,004
Series B convertible preferred stock		—		9,100,616
Restricted stock		58,259		116,518
Stock options		2,939,499		2,102,514
Total		2,997,758		11,720,652

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2020

Commitments And Contingencies Disclosure [Abstract]

Schedule of ROU Assets and Related Lease Liabilities

Information related to the Company’s ROU assets and related lease liabilities were as follows (in thousands except for remaining lease term and discount rate):

	Three Months Ended
	March 31,
	2020		2019
Cash paid for operating lease liabilities	$	740	$	216
Operating lease cost		767		171
Variable lease cost		46		—

	March 31, 2020			December 31, 2019
Current operating lease liabilities	$	2,529		$	2,483
Non-current operating lease liabilities		11,595			12,244
Weighted average remaining lease term in years		5.0			5.1
Weighted average discount rate		3.8	%		3.8	%

Schedule of Maturities of Lease Liabilities

Maturities of lease liabilities as of March 31, 2020 were as follows (in thousands):

	Operating
	Lease
Year Ending December	Commitments
2020 (remaining nine months)	$	2,261
2021		3,086
2022		3,172
2023		3,261
2024		3,008
Thereafter		733
Total		15,521
Less imputed interest		(1,397	)
Total lease liabilities	$	14,124

Organization - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended	3 Months Ended
	Sep. 20, 2019 USD ($) $ / shares shares	Sep. 19, 2019 shares	Aug. 31, 2019	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)
Subsidiary Sale Of Stock [Line Items]
Reverse stock split ratio			6.6084
Reverse stock split ratio, description				6.6084–for-1
Accumulated deficit \| $				$ 124,829	$ 107,205
Cash, and investments \| $						$ 219,000
Common Stock
Subsidiary Sale Of Stock [Line Items]
Conversion of convertible preferred stock into common stock, shares		10,787,861
IPO
Subsidiary Sale Of Stock [Line Items]
Common stock, shares issued	12,578,125
Common stock, price per share \| $ / shares	$ 16.00
Common stock, exercised by underwriters	1,640,625
Proceeds from IPO, net of underwriting discounts and commission and offering costs \| $	$ 183,000
Non-voting Common Stock
Subsidiary Sale Of Stock [Line Items]
Conversion of convertible preferred stock into common stock, shares	6,431,205

Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019	Jan. 01, 2020	Dec. 31, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares reserved for issuance		6,486,455			5,296,732
Shares available for issuance		2,967,576			2,669,264
Accrued share based compensation expense		$ 100,000	$ 0
Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation		$ 24,000
Expects to recognize over a remaining weighted-average period		3 months 18 days
Executive Officer \| Restricted Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	2 years
Issued of common stock	116,518
Grant date fair value per share	$ 1.39
Shares vested		58,259
2018 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of exercise price of stock option on estimated fair value of shares		110.00%
Vesting period		3 years
Shares reserved for issuance		4,384,000
Increase in number of shares				964,487
Outstanding stock percent		4.00%
Shares available for issuance		2,967,576
2018 Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Term of options		10 years
Increase in number of shares		8,768,800
2018 Plan \| Share-based Compensation Award, Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting percentage		25.00%
Vesting period		1 year
2018 Plan \| 10% Stockholder \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Term of options		5 years
2018 Plan \| 10% Stockholder \| Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of voting power		10.00%
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of shares				241,121
Outstanding stock percent		1.00%
Shares available for issuance		521,121			280,000
Percentage of exercise price of stock option on estimated fair value of shares		85.00%
ESPP \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of shares		560,000
Discount rate		15.00%

Stock-Based Compensation - Summary of Stock Option (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding Options, Shares Available for Grant, Beginning balance	2,669,264
Outstanding Options, Shares Available for Grant, Addition - Option pool	964,487
Outstanding Options, Shares Available for Grant, Granted	(679,575)
Outstanding Options, Shares Available for Grant, Cancelled	13,400
Outstanding Options, Shares Available for Grant, Ending balance	2,967,576	2,669,264
Outstanding Options, Shares, Beginning balance	2,289,209
Outstanding Options, Shares, Granted	679,575
Outstanding Options, Shares, Exercised	(15,885)
Outstanding Options, Shares, Cancelled	(13,400)
Outstanding Options, Shares, Ending balance	2,939,499	2,289,209
Outstanding Options, Shares, Exercisable	1,118,904
Outstanding Options, Weighted-Average Exercise Price, Beginning balance	$ 3.36
Outstanding Options, Weighted-Average Exercise Price, Granted	39.93
Outstanding Options, Weighted-Average Exercise Price, Exercised	1.32
Outstanding Options, Weighted-Average Exercise Price, Canceled	20.02
Outstanding Options, Weighted-Average Exercise Price, Ending balance	11.75	$ 3.36
Outstanding Options, Weighted-Average Exercise Price, Exercisable	$ 1.77
Outstanding Options, Weighted Average Remaining Contractual Term (Years)	8 years 3 months 18 days	8 years 1 month 6 days
Outstanding Options, Weighted Average Remaining Contractual Term (Years), Exercisable	6 years 7 months 6 days

Related Party Transactions with its Significant Investor - Additional Information (Details) - USD ($)			1 Months Ended		3 Months Ended		4 Months Ended
	Sep. 20, 2019	Sep. 19, 2019	Jun. 30, 2019	Apr. 30, 2019	Mar. 31, 2020	Mar. 31, 2019	Apr. 30, 2019
Related Party Transaction [Line Items]
Accrued interest on related party loan						$ 125,000
IPO
Related Party Transaction [Line Items]
Issuance of common stock, shares	12,578,125
Common Stock
Related Party Transaction [Line Items]
Shares issued upon conversion of convertible preferred stock		10,787,861
Non-voting Common Stock
Related Party Transaction [Line Items]
Shares issued upon conversion of convertible preferred stock	6,431,205
Haldor Topsøe Holding A/S and Holdco
Related Party Transaction [Line Items]
Proceeds from related party notes receivable				$ 2,500,000
Haldor Topsøe Holding A/S and Holdco \| Common Stock \| IPO
Related Party Transaction [Line Items]
Issuance of common stock, shares	1,250,000				10,289,453
Haldor Topsøe Holding A/S and Holdco \| Series C Convertible Preferred Stock
Related Party Transaction [Line Items]
Preferred stock issued			2,269,838
Preferred stock issued, value			$ 30,000,000
Debt settled			20,000,000
Haldor Topsøe Holding A/S and Holdco \| Non-voting Common Stock \| IPO
Related Party Transaction [Line Items]
Shares issued upon conversion of convertible preferred stock	2,269,838
Haldor Topsøe Holding A/S and Holdco \| Unsecured Promissory Note
Related Party Transaction [Line Items]
Proceeds from loan from related party							$ 15,000,000
Outstanding unsecured promissory note			$ 20,000,000
Accrued interest on related party loan						$ 100,000

Condensed Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	200,000,000	200,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	24,069,806	24,053,921
Common stock, shares outstanding	24,069,806	24,053,921
Non-voting Common Stock
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	6,431,208	6,431,208
Common stock, shares issued	6,431,205	6,431,205
Common stock, shares outstanding	6,431,205	6,431,205

Common Stock and Non-Voting Common Stock - Additional Information (Details)	3 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($) Vote $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Class Of Stock [Line Items]
Common stock, shares authorized	1,000,000,000	1,000,000,000
Preferred stock, shares authorized	200,000,000	200,000,000
Common stock, par value \| $ / shares	$ 0.01	$ 0.01
Preferred stock, par value \| $ / shares	$ 0.01	$ 0.01
Common stock, voting rights	Each share of common stock is entitled to one vote
Number of common stock voting rights held \| Vote	1
Common stock, dividends declared \| $	$ 0	$ 0
Common Stock Including Nonvoting Common Stock
Class Of Stock [Line Items]
Common stock, shares authorized	1,006,431,208	1,006,431,208
Non-voting Common Stock
Class Of Stock [Line Items]
Common stock, shares authorized	6,431,208	6,431,208
Common stock, par value \| $ / shares	$ 0.01	$ 0.01

Commitments and Contingencies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020 Agreement
Lessee Lease Description [Line Items]
Number of lease agreements	2
Offices and Laboratory \| Mountain View, California \| Lease Agreements One
Lessee Lease Description [Line Items]
Lessee operating lease expiry month and year	2024-09
Offices and Laboratory \| Mountain View, California \| Lease Agreements Two
Lessee Lease Description [Line Items]
Lessee operating lease expiry month and year	2025-04

Condensed Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (17,624)	$ (7,470)
Other comprehensive income:
Unrealized gain on investments	162
Comprehensive loss	$ (17,462)	$ (7,470)

Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2020
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment estimated useful life	5 years

Fair Value Measurement - Summary of Investments Measured and Recognized at Fair Value (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 170,704	$ 200,673
Gross Unrealized Gains	312	52
Gross Unrealized Losses	(107)	(9)
Fair Value	170,909	200,716
U.S. Treasury Securities \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	45,242	66,244
Gross Unrealized Gains	227	48
Fair Value	45,469	66,292
Corporate Bonds \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	40,685	39,953
Gross Unrealized Gains		3
Gross Unrealized Losses	(107)
Fair Value	40,578	39,956
Commercial Paper \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	63,606	74,507
Gross Unrealized Gains	1
Gross Unrealized Losses		(9)
Fair Value	63,607	74,498
U.S. Government Agency Securities \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	21,171	19,969
Gross Unrealized Gains	84	1
Fair Value	$ 21,255	$ 19,970

Fair Value Measurement - Summary of Contractual Maturities of Investments (Details) - Fair Value, Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Due in less than one year	$ 158,714	$ 188,743
Due in more than one year	12,195	11,973
Total	$ 170,909	$ 200,716

Balance Sheet Components - Schedule of Property, Plant and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property, plant and equipment, gross	$ 6,169	$ 5,146
Less: Accumulated depreciation	(1,486)	(1,264)
Total property, plant and equipment, net	4,683	3,882
Laboratory Equipment
Property Plant And Equipment [Line Items]
Total property, plant and equipment, gross	4,796	3,800
Office Equipment
Property Plant And Equipment [Line Items]
Total property, plant and equipment, gross	150	150
Leasehold Improvement
Property Plant And Equipment [Line Items]
Total property, plant and equipment, gross	90	78
Construction In Progress
Property Plant And Equipment [Line Items]
Total property, plant and equipment, gross	$ 1,133	$ 1,118

Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Balance Sheet Related Disclosures [Abstract]
Accrued research and development materials and services	$ 1,194	$ 906
Accrued professional services	437	360
Accrued compensation	1,391	2,030
Other	9	9
Total accrued liabilities	$ 3,031	$ 3,305

Common Stock and Non-Voting Common Stock - Schedule of Number of Common Stock Reserved for Future Issuance (Details) - shares	Mar. 31, 2020	Dec. 31, 2019
Stockholders Equity Note [Abstract]
Restricted stock, issued and outstanding	58,259	58,259
Stock options, issued and outstanding	2,939,499	2,289,209
Stock options, future issuance	2,967,576	2,669,264
Employee stock purchase plan, available for future grants	521,121	280,000
Total	6,486,455	5,296,732

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - 2010 Plan, 2018 Plan and ESPP - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,323	$ 139
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	666	105
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 657	$ 34

Net Loss Per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net loss	$ (17,624)	$ (7,470)
Denominator:
Weighted average common shares outstanding used to compute net loss per share, basic and diluted	30,491,463	443,118
Net loss per share attributable to common stockholders	$ (0.58)	$ (16.86)

Net Loss Per Share Attributable to Common Stockholders - Summary of Potentially Dilutive Securities Not Included in the Diluted Per Share Calculations (Details) - shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included in diluted per share calculations	2,997,758	11,720,652
Series A Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included in diluted per share calculations		401,004
Series B Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included in diluted per share calculations		9,100,616
Restricted Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included in diluted per share calculations	58,259	116,518
Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities not included in diluted per share calculations	2,939,499	2,102,514

Commitments and Contingencies - Schedule of Maturities of Lease Liabilities (Details) $ in Thousands	Mar. 31, 2020 USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2020 (remaining nine months)	$ 2,261
2021	3,086
2022	3,172
2023	3,261
2024	3,008
Thereafter	733
Total	15,521
Less imputed interest	(1,397)
Total lease liabilities	$ 14,124