Allowance for Credit Losses - Change in Liability for Off-balance Sheet Credit Exposures (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 237	$ 104	$ 96
Provision charged (credited) to income	(134)	79	8
Balance at end of period	103	237	104
Cumulative Effect, Period of Adoption, Adjustment
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	0	54	0
Balance at end of period		0	54
Cumulative Effect, Period of Adoption, Adjusted Balance
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 237	158	96
Balance at end of period		$ 237	$ 158