Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of year	$ 1,091	$ 1,552	$ 1,442
Additions due to acquisitions	26
Additions for tax positions of current year	32	8	53
Additions for tax positions of prior years	60		69
Reductions for tax positions of prior years	(5)	(296)	(7)
Closure of tax years	(27)
Settlements	(53)	(173)	(5)
Balance at end of year	1,124	1,091	1,552
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	59	78
Federal and State [Member]
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Period Increase (Decrease)	(75)	(410)	45
Foreign [Member]
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Unrecognized Tax Benefits, Period Increase (Decrease)	$ 80	$ (51)	$ 70