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Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
Fair Value Measurements - Narrative (Details) - USD ($)	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	May 13, 2021	Mar. 23, 2021	Jan. 14, 2021	Apr. 06, 2020	Oct. 31, 2018
Derivative [Line Items]
Net cash related to derivative contracts under collateral exchange arrangements		$ 580,000,000	$ 0	$ (632,000,000)	$ 632,000,000
Accumulated other comprehensive loss			1,365,000,000	1,581,000,000
Other current and long-term liabilities			(531,000,000)	(2,178,000,000)	$ 144,000,000
Level 3 \| Fair Value
Derivative [Line Items]
Carrying amounts of deferred purchase price assets			779,000,000	884,000,000
Interest Expense
Derivative [Line Items]
Amount amortized from AOCI into interest expense			189,000,000	128,000,000
Amount expected to be amortized from AOCI into interest expense over next 12 months			203,000,000
Senior Secured Notes due 2025, 3.500%
Derivative [Line Items]
Interest rate, stated percentage									3.50%
Senior Secured Notes due 2050, 4.500%
Derivative [Line Items]
Interest rate, stated percentage									4.50%
Senior Notes
Derivative [Line Items]
Principal Issuances						$ 3,000,000,000	$ 3,800,000,000	$ 3,000,000,000	$ 19,000,000,000
Interest Rate Contract
Derivative [Line Items]
Net cash related to derivative contracts under collateral exchange arrangements				1,200,000,000
Accumulated other comprehensive loss			$ 1,500,000,000	$ 1,600,000,000
Derivative liabilities	$ 2,300,000,000
Cash-collateralized	1,200,000,000
Other current and long-term liabilities	$ 2,300,000,000
Interest Rate Contract \| Cash Flow Hedging
Derivative [Line Items]
Aggregate notional amount										$ 9,600,000,000