Income Taxes - Rollforward of Total Unrecognized Tax Liabilities (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, beginning of period	$ 1,614	$ 2,031	$ 1,595
Tax positions related to current year:
Additions	147	121	138
Reductions	0	0	0
Tax positions related to prior years:
Additions	161	398	405
Reductions	(179)	(481)	0
Settlements	(28)	(454)	(104)
Lapse of statute of limitations	(2)	(1)	(3)
Balance, end of period	$ 1,713	$ 1,614	$ 2,031