XML 32 R21.htm IDEA: XBRL DOCUMENT v3.21.1

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Stock-Based Compensation

Schedule of total employee, director and non-employee stock-based compensation expense recognized

​

​	​	​	​	​	​	​	​
​	​	Three Months Ended
​	​	March 31,
​		2021			2020
General and administrative	​	$	2,737	​	$	2,291	​
Research and development	​		5,556	​		4,221	​
​	​	$	8,293	​	$	6,512	​
​	​	​	​	​	​	​	​
​	​	Three Months Ended					​
​	​	March 31,					​
​	​	2021			2020		​
Stock options	​	$	6,530	​	$	5,882	​
ESPP	​	​	248	​	​	194	​
RSUs	​	​	1,515	​	​	436	​
​	​	$	8,293	​	$	6,512	​

Summary of stock option activity

​

​	​	​	​	​	​	​	​	​	​	​	​
​				Weighted			Weighted		​	​
​	​	​	​	Average			Average		​	​
​	​	Number of	​	Exercise			Remaining		​	Aggregate
​	​	Shares Subject	​	Price			Contractual		​	Intrinsic
​	​	to Outstanding	​	(Per			Term		​	Value
​	​	Options	​	Share)			(in years)		​	(in thousands)
Balance at December 31, 2020		7,751,789	​	$	26.23	​	​	7.00	​	$	134,941
Options granted		1,321,917	​	$	43.24	​	​	​	​	​	​
Options forfeited		(64,824)	​	$	33.00	​	​	​	​	​	​
Options exercised		(230,701)	​	$	23.14	​	​	​	​	​	​
Balance at March 31, 2021		8,778,181	​	$	28.82	​	​	7.25	​	$	125,395
Exercisable	​	4,963,607	​	$	22.73	​	​	5.95	​	$	100,938

Schedule of weighted average assumptions used for estimation of fair value of stock options

​

​	​	​	​	​	​
​	​	Options			​
​	​	Three Months Ended			​
​	​	March 31,			​
​		2021		2020
Expected term (years)	​	6.2		6.3	​
Expected volatility	​	55.6	%	53.9	%
Risk-free interest rate	​	1.02	%	1.71	%
Expected dividend yield	​	—	%	—	%

Schedule of weighted average assumptions used for estimation of fair value of ESPP

​

​	​	​	​	​	​
​	​	ESPP			​
​	​	Three Months Ended			​
​	​	March 31,			​
​		2021		2020
Expected term (years)		0.5 - 2.0		0.5 - 2.0	​
Expected volatility	​	50.8 - 66.4	%	50.8	%
Risk-free interest rate		0.09 - 1.65	%	1.56 - 1.65	%
Expected dividend yield	​	—	%	—	%

Summary of restricted stock unity activity

​

​	​	​	​	​	​
​	​	​	​	Weighted
​	​	Restricted	​	Average Grant
​	​	Stock	​	Date Fair Value
​	​	Units	​	(Per unit)
​	​	​	​	​	​
Unvested RSUs at December 31, 2020		358,825	​	$	33.04
Granted		247,050	​	​	43.11
Vested		(117,808)	​	​	31.75
Forfeited		(9,071)	​	​	32.36
Unvested RSUs at March 31, 2021		478,996	​	$	38.56

X

- References

No definition available.

+ Details

Name:	us-gaap_DisclosureOfCompensationRelatedCostsSharebasedPaymentsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the changes in outstanding nonvested restricted stock shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_NonvestedRestrictedStockSharesActivityTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of allocation of amount expensed and capitalized for award under share-based payment arrangement to statement of income or comprehensive income and statement of financial position. Includes, but is not limited to, corresponding line item in financial statement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901

+ Details

Name:	us-gaap_ScheduleOfEmployeeServiceShareBasedCompensationAllocationOfRecognizedPeriodCostsTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the significant assumptions used during the year to estimate the fair value of employee stock purchase plans, including, but not limited to: (a) expected term, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ScheduleOfShareBasedPaymentAwardEmployeeStockPurchasePlanValuationAssumptionsTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

Name:	us-gaap_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionsTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Tabular disclosure of the change in stock options.

+ References

No definition available.

+ Details

Name:	us-gaap_ScheduleOfStockOptionsRollForwardTableTextBlock
Namespace Prefix:	us-gaap_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration