Financial Instruments and Fair Value Measurements - Summary of Cash and Available-for-Sale Securities by Significant Investment Category (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 2,618,345	$ 1,024,106
Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,242,194	1,259,980
Unrealized Gains	4,413	3,047
Unrealized Losses	(151)	(40)
Fair Value	5,246,456	1,262,987
Level 2 \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Fair Value	2,623,850	235,876
Level 2 \| Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	1,983,758	867,124
Level 2 \| Non- Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	638,848	159,987
Cash and Cash Equivalents \| Level 1
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	2,623,849	225,874
Unrealized Gains	1	0
Unrealized Losses	0	0
Fair Value	2,623,850	225,874
Cash and Cash Equivalents \| Level 1 \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Fair Value	2,623,850	225,874
Cash and Cash Equivalents \| Level 1 \| Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	0	0
Cash and Cash Equivalents \| Level 1 \| Non- Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	0	0
Certificates of deposit \| Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	238,774	82,028
Unrealized Gains	49	79
Unrealized Losses	(4)	(6)
Fair Value	238,819	82,101
Certificates of deposit \| Level 2 \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Fair Value	0	10,002
Certificates of deposit \| Level 2 \| Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	215,389	69,197
Certificates of deposit \| Level 2 \| Non- Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	23,430	2,902
U.S. treasury securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	491,549	117,891
Unrealized Gains	69	260
Unrealized Losses	0	(2)
Fair Value	491,618	118,149
U.S. treasury securities \| Level 2 \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Fair Value	0	0
U.S. treasury securities \| Level 2 \| Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	491,618	110,186
U.S. treasury securities \| Level 2 \| Non- Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	0	7,963
Debt securities of U.S. government agencies and corporate entities \| Level 2
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,888,022	834,187
Unrealized Gains	4,294	2,708
Unrealized Losses	(147)	(32)
Fair Value	1,892,169	836,863
Debt securities of U.S. government agencies and corporate entities \| Level 2 \| Cash and Cash Equivalents
Debt Securities, Available-for-sale [Line Items]
Fair Value	0	0
Debt securities of U.S. government agencies and corporate entities \| Level 2 \| Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	1,276,751	687,741
Debt securities of U.S. government agencies and corporate entities \| Level 2 \| Non- Current Marketable Securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 615,418	$ 149,122

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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