Loans and leases and allowance for credit losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	$ 2,129	$ 1,925	$ 1,469
Allowance on acquired PCD loans			99
Provision for credit losses	610	645	517
Charge-offs	(713)	(570)	(303)
Recoveries	158	129	143
Net charge-offs	(555)	(441)	(160)
Ending balance	2,184	2,129	1,925
Commercial and industrial
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	620	568	335
Allowance on acquired PCD loans			48
Provision for credit losses	429	132	244
Charge-offs	(316)	(132)	(119)
Recoveries	36	52	60
Net charge-offs	(280)	(80)	(59)
Ending balance	769	620	568
Commercial Real Estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	764	611	506
Allowance on acquired PCD loans			49
Provision for credit losses	(89)	394	93
Charge-offs	(134)	(253)	(60)
Recoveries	58	12	23
Net charge-offs	(76)	(241)	(37)
Ending balance	599	764	611
Residential Real Estate
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	116	115	72
Allowance on acquired PCD loans			2
Provision for credit losses	(8)	4	43
Charge-offs	(6)	(10)	(12)
Recoveries	6	7	10
Net charge-offs	0	(3)	(2)
Ending balance	108	116	115
Consumer:
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning balance	629	631	556
Allowance on acquired PCD loans			0
Provision for credit losses	278	115	137
Charge-offs	(257)	(175)	(112)
Recoveries	58	58	50
Net charge-offs	(199)	(117)	(62)
Ending balance	$ 708	$ 629	$ 631