Fair Value Measurements - Recurring Fair Value Measurements (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets
Marketable securities	$ 447,046	$ 452,875
Fair Value, Measurements, Recurring
Assets
Total assets	1,602,658	1,666,418
Fair Value, Measurements, Recurring \| Money market funds
Assets
Money market funds	1,155,612	1,213,543
Fair Value, Measurements, Recurring \| U.S. government securities
Assets
Marketable securities	412,453	418,284
Fair Value, Measurements, Recurring \| Commercial paper
Assets
Marketable securities	15,972	13,878
Fair Value, Measurements, Recurring \| Asset-backed securities
Assets
Marketable securities	0	2,002
Fair Value, Measurements, Recurring \| Corporate debt securities
Assets
Marketable securities	18,621	18,711
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1
Assets
Total assets	1,568,065	1,631,827
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1 \| Money market funds
Assets
Money market funds	1,155,612	1,213,543
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1 \| U.S. government securities
Assets
Marketable securities	412,453	418,284
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1 \| Commercial paper
Assets
Marketable securities	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1 \| Asset-backed securities
Assets
Marketable securities	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 1 \| Corporate debt securities
Assets
Marketable securities	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2
Assets
Total assets	34,593	34,591
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| Money market funds
Assets
Money market funds	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| U.S. government securities
Assets
Marketable securities	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| Commercial paper
Assets
Marketable securities	15,972	13,878
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| Asset-backed securities
Assets
Marketable securities	0	2,002
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 2 \| Corporate debt securities
Assets
Marketable securities	18,621	18,711
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3
Assets
Total assets	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3 \| Money market funds
Assets
Money market funds	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3 \| U.S. government securities
Assets
Marketable securities	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3 \| Commercial paper
Assets
Marketable securities	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3 \| Asset-backed securities
Assets
Marketable securities	0	0
Fair Value, Measurements, Recurring \| Fair Value, Inputs, Level 3 \| Corporate debt securities
Assets
Marketable securities	$ 0	$ 0

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- Definition

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
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- Definition

Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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-SubTopic 10
-Section S99
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