Derivative Financial Instruments - Cash Flow and Fair Value Hedges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flow hedges
Derivative [Line Items]
Net unrecognized after-tax gain (loss) on terminated hedges recorded in AOCI (to be recognized in earnings through 2022)	$ (9)	$ (64)
Estimated portion of net after-tax gain (loss) on terminated hedges to be reclassified from AOCI into earnings during the next 12 months	(9)	(42)
Fair Value Hedges
Derivative [Line Items]
Unrecognized pre-tax net gain (loss) on terminated hedges (to be recognized as interest primarily through 2029)	767	862
Portion of pre-tax net gain (loss) on terminated hedges to be recognized as a change in interest during the next 12 months	$ 231	$ 292