Income Taxes - Changes in Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at beginning of year	$ (454)	$ (451)
Additions for tax positions of the current year	(32)	(42)
Additions for tax positions of prior years	(166)	(31)
Reductions for tax positions of prior years	42	35
Settlements with tax authorities	95	12
Lapse of statute of limitations	13	23
Balance at end of year	(502)	(454)	$ (451)
Tax expense (benefit) due to unrecognized tax benefits (1)	$ 201	$ 35	$ (24)