Loans and Leases and the Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 2,204	$ 1,998	$ 2,129	$ 1,925
Provision for credit losses	120	150	470	420
Charge-offs	154	122	497	379
Recoveries	34	26	102	86
Net charge-offs	(120)	(96)	(395)	(293)
Ending balance	2,204	2,052	2,204	2,052
Commercial and industrial
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	790	583	620	568
Provision for credit losses	52	40	365	73
Charge-offs	64	26	220	70
Recoveries	14	7	27	33
Net charge-offs	(50)	(19)	(193)	(37)
Ending balance	792	604	792	604
Commercial Real Estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	658	694	764	611
Provision for credit losses	1	79	(60)	287
Charge-offs	24	52	92	180
Recoveries	4	5	27	8
Net charge-offs	(20)	(47)	(65)	(172)
Ending balance	639	726	639	726
Residential Real Estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	110	118	116	115
Provision for credit losses	(5)	(3)	(11)	(1)
Charge-offs	1	1	4	4
Recoveries	1	0	4	4
Net charge-offs	0	(1)	0	0
Ending balance	105	114	105	114
Consumer:
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	646	603	629	631
Provision for credit losses	72	34	176	61
Charge-offs	65	43	181	125
Recoveries	15	14	44	41
Net charge-offs	(50)	(29)	(137)	(84)
Ending balance	$ 668	$ 608	$ 668	$ 608