Investments and Fair Value Measurement - Fair Value on a Recurring Basis (Details) - Recurring - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Financial Assets
Non-marketable debt securities:	$ 4,534	$ 3,817
Note receivable from a related party	81	83
Total financial assets	8,493	6,338
Money market funds
Financial Assets
Cash and cash equivalents	2,155	2,386
Commercial paper
Financial Assets
Non-marketable debt securities:	440	611
U.S. government and agency securities
Financial Assets
Non-marketable debt securities:	322	542
Corporate bonds
Financial Assets
Non-marketable debt securities:	181	323
Non-marketable debt securities
Financial Assets
Non-marketable debt securities:	3,591	2,341
Non-marketable equity securities
Financial Assets
Non-marketable equity securities	1,723	52
Level 1
Financial Assets
Note receivable from a related party	0	0
Total financial assets	2,155	2,386
Level 1 \| Money market funds
Financial Assets
Cash and cash equivalents	2,155	2,386
Level 1 \| Commercial paper
Financial Assets
Non-marketable debt securities:	0	0
Level 1 \| U.S. government and agency securities
Financial Assets
Non-marketable debt securities:	0	0
Level 1 \| Corporate bonds
Financial Assets
Non-marketable debt securities:	0	0
Level 1 \| Non-marketable debt securities
Financial Assets
Non-marketable debt securities:	0	0
Level 1 \| Non-marketable equity securities
Financial Assets
Non-marketable equity securities	0	0
Level 2
Financial Assets
Note receivable from a related party	0	0
Total financial assets	943	1,476
Level 2 \| Money market funds
Financial Assets
Cash and cash equivalents	0	0
Level 2 \| Commercial paper
Financial Assets
Non-marketable debt securities:	440	611
Level 2 \| U.S. government and agency securities
Financial Assets
Non-marketable debt securities:	322	542
Level 2 \| Corporate bonds
Financial Assets
Non-marketable debt securities:	181	323
Level 2 \| Non-marketable debt securities
Financial Assets
Non-marketable debt securities:	0	0
Level 2 \| Non-marketable equity securities
Financial Assets
Non-marketable equity securities	0	0
Level 3
Financial Assets
Note receivable from a related party	81	83
Total financial assets	5,395	2,476
Level 3 \| Money market funds
Financial Assets
Cash and cash equivalents	0	0
Level 3 \| Commercial paper
Financial Assets
Non-marketable debt securities:	0	0
Level 3 \| U.S. government and agency securities
Financial Assets
Non-marketable debt securities:	0	0
Level 3 \| Corporate bonds
Financial Assets
Non-marketable debt securities:	0	0
Level 3 \| Non-marketable debt securities
Financial Assets
Non-marketable debt securities:	3,591	2,341
Level 3 \| Non-marketable equity securities
Financial Assets
Non-marketable equity securities	$ 1,723	$ 52

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).

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Amount of investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI).

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Fair value portion of an agreement for an unconditional promise by the maker to pay the holder a definite sum of money at a future date.

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