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Investments and Fair Value Measurement - Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Financial Assets
Non-marketable equity securities	$ 283		$ 6,576
Call Option
Financial Liabilities
MLU B.V. Call Option	193	$ 230
Recurring
Financial Assets
Non-marketable debt securities			3,817
Non-marketable equity securities	32		52
Marketable equity securities	11,359		0
Notes receivable from a related party	132		83
Total financial assets	11,523		6,338
Financial Liabilities
Total financial liabilities	193		0
Recurring \| Call Option
Financial Liabilities
MLU B.V. Call Option	193		0
Recurring \| Level 1
Financial Assets
Non-marketable equity securities	0		0
Marketable equity securities	11,359		0
Notes receivable from a related party	0		0
Total financial assets	11,359		2,386
Financial Liabilities
Total financial liabilities	0		0
Recurring \| Level 1 \| Call Option
Financial Liabilities
MLU B.V. Call Option	0		0
Recurring \| Level 2
Financial Assets
Non-marketable equity securities	0		0
Marketable equity securities	0		0
Notes receivable from a related party	0		0
Total financial assets	0		1,476
Financial Liabilities
Total financial liabilities	0		0
Recurring \| Level 2 \| Call Option
Financial Liabilities
MLU B.V. Call Option	0		0
Recurring \| Level 3
Financial Assets
Non-marketable equity securities	32		52
Marketable equity securities	0		0
Notes receivable from a related party	132		83
Total financial assets	164		2,476
Financial Liabilities
Total financial liabilities	193		0
Recurring \| Level 3 \| Call Option
Financial Liabilities
MLU B.V. Call Option	193		0
Recurring \| Money market funds
Financial Assets
Cash and cash equivalents	0		2,386
Recurring \| Money market funds \| Level 1
Financial Assets
Cash and cash equivalents	0		2,386
Recurring \| Money market funds \| Level 2
Financial Assets
Cash and cash equivalents	0		0
Recurring \| Money market funds \| Level 3
Financial Assets
Cash and cash equivalents	0		0
Recurring \| Commercial paper
Financial Assets
Non-marketable debt securities	0		611
Recurring \| Commercial paper \| Level 1
Financial Assets
Non-marketable debt securities	0		0
Recurring \| Commercial paper \| Level 2
Financial Assets
Non-marketable debt securities	0		611
Recurring \| Commercial paper \| Level 3
Financial Assets
Non-marketable debt securities	0		0
Recurring \| U.S. government and agency securities
Financial Assets
Non-marketable debt securities	0		542
Recurring \| U.S. government and agency securities \| Level 1
Financial Assets
Non-marketable debt securities	0		0
Recurring \| U.S. government and agency securities \| Level 2
Financial Assets
Non-marketable debt securities	0		542
Recurring \| U.S. government and agency securities \| Level 3
Financial Assets
Non-marketable debt securities	0		0
Recurring \| Corporate bonds
Financial Assets
Non-marketable debt securities	0		323
Recurring \| Corporate bonds \| Level 1
Financial Assets
Non-marketable debt securities	0		0
Recurring \| Corporate bonds \| Level 2
Financial Assets
Non-marketable debt securities	0		323
Recurring \| Corporate bonds \| Level 3
Financial Assets
Non-marketable debt securities	0		0
Recurring \| Non-marketable debt securities
Financial Assets
Non-marketable debt securities	0		2,341
Recurring \| Non-marketable debt securities \| Level 1
Financial Assets
Non-marketable debt securities	0		0
Recurring \| Non-marketable debt securities \| Level 2
Financial Assets
Non-marketable debt securities	0		0
Recurring \| Non-marketable debt securities \| Level 3
Financial Assets
Non-marketable debt securities	$ 0		$ 2,341