Financial Instruments and Fair Value Measurements - Financial Assets Measured At Fair Value On a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Level 2
Debt Securities, Available-for-sale [Line Items]
AFS	$ 5,246,456	$ 1,262,987
Certificates of deposit \| Level 2
Debt Securities, Available-for-sale [Line Items]
AFS	238,819	82,101
U.S. treasury securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
AFS	491,618	118,149
Debt securities of U.S. government agencies and corporate entities \| Level 2
Debt Securities, Available-for-sale [Line Items]
AFS	1,892,169	836,863
Fair value recurring
Debt Securities, Available-for-sale [Line Items]
Derivative instruments	293
Assets, Fair Value Disclosure	3,243,846	1,037,113
Fair value recurring \| Level 1
Debt Securities, Available-for-sale [Line Items]
Derivative instruments	0
Assets, Fair Value Disclosure	620,947	0
Fair value recurring \| Level 2
Debt Securities, Available-for-sale [Line Items]
Derivative instruments	293
Assets, Fair Value Disclosure	2,622,899	1,037,113
Fair value recurring \| Money market funds
Debt Securities, Available-for-sale [Line Items]
AFS	620,947
Fair value recurring \| Money market funds \| Level 1
Debt Securities, Available-for-sale [Line Items]
AFS	620,947
Fair value recurring \| Money market funds \| Level 2
Debt Securities, Available-for-sale [Line Items]
AFS	0
Fair value recurring \| Certificates of deposit
Debt Securities, Available-for-sale [Line Items]
AFS	238,819	82,101
Fair value recurring \| Certificates of deposit \| Level 1
Debt Securities, Available-for-sale [Line Items]
AFS	0	0
Fair value recurring \| Certificates of deposit \| Level 2
Debt Securities, Available-for-sale [Line Items]
AFS	238,819	82,101
Fair value recurring \| U.S. treasury securities
Debt Securities, Available-for-sale [Line Items]
AFS	491,618	118,149
Fair value recurring \| U.S. treasury securities \| Level 1
Debt Securities, Available-for-sale [Line Items]
AFS	0	0
Fair value recurring \| U.S. treasury securities \| Level 2
Debt Securities, Available-for-sale [Line Items]
AFS	491,618	118,149
Fair value recurring \| Debt securities of U.S. government agencies and corporate entities
Debt Securities, Available-for-sale [Line Items]
AFS	1,892,169	836,863
Fair value recurring \| Debt securities of U.S. government agencies and corporate entities \| Level 1
Debt Securities, Available-for-sale [Line Items]
AFS	0	0
Fair value recurring \| Debt securities of U.S. government agencies and corporate entities \| Level 2
Debt Securities, Available-for-sale [Line Items]
AFS	$ 1,892,169	$ 836,863

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 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
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-SubTopic 210
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Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset.

+ References

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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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