Other Assets - Identifiable Intangible Assets by Type (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Dec. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	$ 3,688	$ 3,688	$ 3,711
Accumulated amortization	(2,347)	(2,347)	(1,702)
Net carrying value	1,341	1,341	2,009
GreenSky
Finite-Lived Intangible Assets [Line Items]
Net carrying value	110	110
Intangible assets write-down	506	506
PFM
Finite-Lived Intangible Assets [Line Items]
Net carrying value	165	165
Customer lists and merchant relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	3,208	3,208	3,225
Accumulated amortization	(1,904)	(1,904)	(1,275)
Net carrying value	1,304	1,304	1,950
Acquired leases and other
Finite-Lived Intangible Assets [Line Items]
Gross carrying value	480	480	486
Accumulated amortization	(443)	(443)	(427)
Net carrying value	$ 37	$ 37	$ 59