Fair Value Measurements - Recurring Basis (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value		$ (26)
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value		0
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value		(26)
Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value		0
Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	$ 9,358	8,543
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	9,352	8,543
Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	6	0
Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0	0
Recurring | Cash and cash equivalents | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	8,906	8,345
Recurring | Cash and cash equivalents | Foreign government treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	30	34
Recurring | Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	8,906	8,345
Recurring | Cash and cash equivalents | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign government treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	30	34
Recurring | Cash and cash equivalents | Significant Other Observable Inputs (Level 2) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0	0
Recurring | Cash and cash equivalents | Significant Other Observable Inputs (Level 2) | Foreign government treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0	0
Recurring | Cash and cash equivalents | Significant Unobservable Inputs (Level 3) | Money market funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0	0
Recurring | Cash and cash equivalents | Significant Unobservable Inputs (Level 3) | Foreign government treasury bills
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0	0
Recurring | Other current assets | U.S. treasuries and government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	322	164
Recurring | Other current assets | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	94
Recurring | Other current assets | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. treasuries and government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	322	164
Recurring | Other current assets | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	94
Recurring | Other current assets | Significant Other Observable Inputs (Level 2) | U.S. treasuries and government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0	0
Recurring | Other current assets | Significant Other Observable Inputs (Level 2) | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0
Recurring | Other current assets | Significant Unobservable Inputs (Level 3) | U.S. treasuries and government agency securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0	0
Recurring | Other current assets | Significant Unobservable Inputs (Level 3) | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0
Recurring | Other current assets & Other assets | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	6
Recurring | Other current assets & Other assets | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0
Recurring | Other current assets & Other assets | Significant Other Observable Inputs (Level 2) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	6
Recurring | Other current assets & Other assets | Significant Unobservable Inputs (Level 3) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets at fair value	0
Recurring | Accrued expenses and other liabilities | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts not designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value		(2)
Recurring | Accrued expenses and other liabilities | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	(8)	(24)
Recurring | Accrued expenses and other liabilities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts not designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value		0
Recurring | Accrued expenses and other liabilities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	0	0
Recurring | Accrued expenses and other liabilities | Significant Other Observable Inputs (Level 2) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts not designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value		(2)
Recurring | Accrued expenses and other liabilities | Significant Other Observable Inputs (Level 2) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	(8)	(24)
Recurring | Accrued expenses and other liabilities | Significant Unobservable Inputs (Level 3) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts not designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value		0
Recurring | Accrued expenses and other liabilities | Significant Unobservable Inputs (Level 3) | Foreign currency forward contracts designated as hedges | Foreign currency forward contracts designated as hedges
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities at fair value	$ 0	$ 0