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Cash Equivalents and Marketable Securities - Schedule of Fair Value and Amortized Cost of Cash Equivalents and Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Marketable Securities [Line Items]
Amortized Cost	$ 915,840	$ 669,831
Gross Unrealized Gains	72	268
Gross Unrealized Losses	(137)	(12)
Fair Value	915,775	670,087
Short-term Marketable Securities [Member]
Marketable Securities [Line Items]
Fair Value	225,417	472,213
Long-term Marketable Securities [Member]
Marketable Securities [Line Items]
Fair Value	317,511	79,995
U.S. Treasury Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	249,817	202,674
Gross Unrealized Gains	41	27
Gross Unrealized Losses	(97)
Fair Value	249,761	202,701
U.S. Government Agency Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	103,950	205,558
Gross Unrealized Gains	25	207
Gross Unrealized Losses	(14)	(1)
Fair Value	103,961	205,764
Corporate Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	230,724	211,086
Gross Unrealized Gains	6	34
Gross Unrealized Losses	(26)	(11)
Fair Value	230,704	211,109
Money Market Funds [Member]
Marketable Securities [Line Items]
Amortized Cost	331,349	50,513
Fair Value	331,349	50,513
Cash Equivalents [Member]
Marketable Securities [Line Items]
Fair Value	$ 372,847	$ 117,879

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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