Allowance for Credit Losses - Change in Liability for Off-balance Sheet Credit Exposures (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Off-Balance Sheet, Credit Loss, Liability [Roll Forward]
Balance at beginning of period	$ 84	$ 155	$ 103	$ 237
Provision charged (credited) to income	5	(27)	(14)	(109)
Balance at end of period	$ 89	$ 128	$ 89	$ 128