Fair Value Measurements - Schedule of Fair Value of Financial Assets (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2022	Dec. 31, 2021
Financial Assets:
Marketable Securities, Fair Value	$ 2,729,748	$ 2,742,571
Total Financial Assets, Fair Value	2,995,069	3,013,121
Fair Value to Amortized Cost
Amortized Cost	2,757,702	2,748,697
Unrealized Gains	38	144
Unrealized Losses	(27,992)	(6,270)
Fair Value	2,729,748	2,742,571
Commercial paper
Financial Assets:
Marketable Securities, Fair Value	95,239	141,274
Fair Value to Amortized Cost
Amortized Cost	95,239	141,274
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	95,239	141,274
Certificate of deposits
Financial Assets:
Marketable Securities, Fair Value	37,330	44,931
Fair Value to Amortized Cost
Fair Value	37,330	44,931
U.S. government notes
Financial Assets:
Marketable Securities, Fair Value	1,093,921	1,057,810
Fair Value to Amortized Cost
Amortized Cost	1,106,454	1,060,716
Unrealized Gains	16	3
Unrealized Losses	(12,549)	(2,909)
Fair Value	1,093,921	1,057,810
Corporate bonds
Financial Assets:
Marketable Securities, Fair Value	1,265,406	1,252,226
Fair Value to Amortized Cost
Amortized Cost	1,278,474	1,255,149
Unrealized Gains	20	105
Unrealized Losses	(13,088)	(3,028)
Fair Value	1,265,406	1,252,226
Agency securities
Financial Assets:
Marketable Securities, Fair Value	275,182	291,261
Fair Value to Amortized Cost
Amortized Cost	277,535	291,558
Unrealized Gains	2	36
Unrealized Losses	(2,355)	(333)
Fair Value	275,182	291,261
Marketable equity securities
Financial Assets:
Marketable Securities, Fair Value	21,811	0
Fair Value to Amortized Cost
Unrealized Gains	13,500
Fair Value	21,811	0
Fair value of securities reclassified	8,300
Marketable Securities
Financial Assets:
Marketable Securities, Fair Value	2,788,889	2,787,502
Fair Value to Amortized Cost
Fair Value	2,788,889	2,787,502
Money market funds - restricted
Financial Assets:
Other Assets, Fair Value	4,258	4,237
Level I
Financial Assets:
Total Financial Assets, Fair Value	1,321,912	1,283,429
Level I \| Commercial paper
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level I \| Certificate of deposits
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level I \| U.S. government notes
Financial Assets:
Marketable Securities, Fair Value	1,093,921	1,057,810
Fair Value to Amortized Cost
Fair Value	1,093,921	1,057,810
Level I \| Corporate bonds
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level I \| Agency securities
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level I \| Marketable equity securities
Financial Assets:
Marketable Securities, Fair Value	21,811	0
Fair Value to Amortized Cost
Fair Value	21,811	0
Level I \| Marketable Securities
Financial Assets:
Marketable Securities, Fair Value	1,115,732	1,057,810
Fair Value to Amortized Cost
Fair Value	1,115,732	1,057,810
Level I \| Money market funds - restricted
Financial Assets:
Other Assets, Fair Value	4,258	4,237
Level II
Financial Assets:
Total Financial Assets, Fair Value	1,673,157	1,729,692
Level II \| Commercial paper
Financial Assets:
Marketable Securities, Fair Value	95,239	141,274
Fair Value to Amortized Cost
Fair Value	95,239	141,274
Level II \| Certificate of deposits
Financial Assets:
Marketable Securities, Fair Value	37,330	44,931
Fair Value to Amortized Cost
Fair Value	37,330	44,931
Level II \| U.S. government notes
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level II \| Corporate bonds
Financial Assets:
Marketable Securities, Fair Value	1,265,406	1,252,226
Fair Value to Amortized Cost
Fair Value	1,265,406	1,252,226
Level II \| Agency securities
Financial Assets:
Marketable Securities, Fair Value	275,182	291,261
Fair Value to Amortized Cost
Fair Value	275,182	291,261
Level II \| Marketable equity securities
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level II \| Marketable Securities
Financial Assets:
Marketable Securities, Fair Value	1,673,157	1,729,692
Fair Value to Amortized Cost
Fair Value	1,673,157	1,729,692
Level II \| Money market funds - restricted
Financial Assets:
Other Assets, Fair Value	0	0
Level III
Financial Assets:
Total Financial Assets, Fair Value	0	0
Level III \| Commercial paper
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level III \| Certificate of deposits
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level III \| U.S. government notes
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level III \| Corporate bonds
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level III \| Agency securities
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level III \| Marketable equity securities
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level III \| Marketable Securities
Financial Assets:
Marketable Securities, Fair Value	0	0
Fair Value to Amortized Cost
Fair Value	0	0
Level III \| Money market funds - restricted
Financial Assets:
Other Assets, Fair Value	0	0
Money market funds
Financial Assets:
Cash Equivalents, Fair Value	201,922	221,382
Money market funds \| Level I
Financial Assets:
Cash Equivalents, Fair Value	201,922	221,382
Money market funds \| Level II
Financial Assets:
Cash Equivalents, Fair Value	0	0
Money market funds \| Level III
Financial Assets:
Cash Equivalents, Fair Value	$ 0	$ 0

Debt Securities, Available-for-Sale, Reclassification

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

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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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Amortized cost 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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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes 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.

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