Loans and Allowance for Credit Losses - Summary of Financing Receivable credit losses charged-off by portfolio class (Detail) - USD ($) $ in Millions		3 Months Ended	6 Months Ended
		Jun. 30, 2023	Jun. 30, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Originated in 2023		$ 53	$ 53
Originated in 2022		123	227
Originated in 2021		72	87
Originated in 2020		33	43
Originated in 2019		30	46
Originated prior to 2019		129	183
Revolving		287	557
Revolving converted to term		28	28
Total charge-offs		755	1,224
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Originated in 2023		7	7
Originated in 2022		34	40
Originated in 2021		4	8
Originated in 2020		6	10
Originated in 2019		2	7
Originated prior to 2019		17	28
Revolving		40	73
Total charge-offs		110	173
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Originated in 2022	[1]		88
Originated in 2021	[1]	17	17
Originated in 2019	[1]		3
Originated prior to 2019	[1]	14	46
Total charge-offs	[1]	31	154
Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Originated in 2021	[2]	5	5
Originated in 2020	[2]	8	8
Originated in 2019	[2]	15	16
Originated prior to 2019	[2]	93	96
Total charge-offs	[2]	121	125
Credit Card Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Revolving		242	457
Total charge-offs		242	457
Other Retail Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Originated in 2023	[3]	46	46
Originated in 2022	[3]	89	99
Originated in 2021	[3]	46	57
Originated in 2020	[3]	19	25
Originated in 2019	[3]	13	20
Originated prior to 2019	[3]	5	13
Revolving	[3]	5	27
Revolving converted to term	[3]	28	28
Total charge-offs	[3]	$ 251	$ 315

[1] Includes $91 million of charge-offs in the first quarter of 2023 related to uncollectible amounts on acquired loans.

[2] Includes $117 million of charge-offs related to balance sheet repositioning and capital management actions taken in the second quarter of 2023.

[3] Includes $192 million of charge-offs related to balance sheet repositioning and capital management actions taken in the second quarter of 2023.