Marketable Securities - Summary of Marketable Securities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 765,321	$ 542,996
Unrealized Gains	29	321
Unrealized Losses	(173)	(216)
Fair Value	765,177	543,101
Current:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	703,949	445,283
Unrealized Gains	29	311
Unrealized Losses	(114)	(101)
Fair Value	703,864	445,493
Current: \| U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	85,256	113,559
Unrealized Gains	2	134
Unrealized Losses	(7)	(21)
Fair Value	85,251	113,672
Current: \| Government securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	76,980	108,263
Unrealized Gains	16	37
Unrealized Losses	0	(8)
Fair Value	76,996	108,292
Current: \| Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	541,713	223,461
Unrealized Gains	11	140
Unrealized Losses	(107)	(72)
Fair Value	541,617	223,529
Non-current:
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	61,372	97,713
Unrealized Gains	0	10
Unrealized Losses	(59)	(115)
Fair Value	61,313	97,608
Non-current: \| U.S. Treasuries
Debt Securities, Available-for-sale [Line Items]
Amortized Cost		15,147
Unrealized Gains		0
Unrealized Losses		(10)
Fair Value		15,137
Non-current: \| Government securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	25,000	26,831
Unrealized Gains	0	8
Unrealized Losses	(20)	0
Fair Value	24,980	26,839
Non-current: \| Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	36,372	55,735
Unrealized Gains	0	2
Unrealized Losses	(39)	(105)
Fair Value	$ 36,333	$ 55,632

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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Amount, before tax, of unrealized loss 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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Amount excluding accrued interest, of 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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