Allowance for Credit Losses - Loan and Leases Considered Nonaccrual and Interest Income Recognized on Loans (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2023	Jan. 01, 2022	Jan. 01, 2021	Dec. 31, 2020
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	$ 986	$ 997	$ 789
Amortized Cost without Allowance	1,180	1,442	1,271
Total	2,166	2,439	2,060
Amortized Cost				$ 2,439	$ 2,060	$ 1,893
Interest Income Recognized	78	77	59
Commercial and Industrial [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	397	212					$ 153
Amortized Cost without Allowance	273	292					218
Total	670	504					371
Amortized Cost				504	371	433
Interest Income Recognized	22	26	23
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	288	366	199
Amortized Cost without Allowance	581	874	720
Total	869	1,240	919
Amortized Cost				1,240	919	650
Interest Income Recognized	29	14	5
Residential Builder and Developer [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	3	1	1
Amortized Cost without Allowance			2
Total	3	1	3
Amortized Cost				1	3	1
Interest Income Recognized		2	1
Other Commercial Construction [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	71	59					30
Amortized Cost without Allowance	100	66					81
Total	171	125					111
Amortized Cost				125	111	114
Interest Income Recognized	2	4	1
Residential [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	81	147					198
Amortized Cost without Allowance	134	125					158
Total	215	272					356
Amortized Cost				272	356	366
Interest Income Recognized	15	25	24
Residential Limited Documentation [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	19	48					80
Amortized Cost without Allowance	36	30					43
Total	55	78					123
Amortized Cost				78	123	147
Interest Income Recognized	2	1
Home Equity Lines and Loans [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	42	43	32
Amortized Cost without Allowance	39	42	38
Total	81	85	70
Amortized Cost				85	70	79
Interest Income Recognized	7	4	4
Recreational Finance [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	24	37	22
Amortized Cost without Allowance	12	8	6
Total	36	45	28
Amortized Cost				45	28	26
Interest Income Recognized	1	1	$ 1
Automobile [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	9	35					29
Amortized Cost without Allowance	5	5					5
Total	14	40					34
Amortized Cost				40	34	39
Other [Member]
Financing Receivable, Impaired [Line Items]
Amortized Cost with Allowance	52	49					45
Total	$ 52	$ 49					$ 45
Amortized Cost				$ 49	$ 45	$ 38