Loans and Leases and the Allowance for Credit Losses - Changes in Allowance for Credit Losses (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	$ 2,129	$ 1,925
Provision for credit losses	200	120
Net charge-offs
Charge-offs	(163)	(95)
Recoveries	25	25
Net charge-offs	(138)	(70)
Ending balance	2,191	1,975
Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	620	568
Provision for credit losses	137	21
Net charge-offs
Charge-offs	(78)	(20)
Recoveries	5	10
Net charge-offs	(73)	(10)
Ending balance	684	579
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	764	611
Provision for credit losses	9	86
Net charge-offs
Charge-offs	(25)	(29)
Recoveries	6	1
Net charge-offs	(19)	(28)
Ending balance	754	669
Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	116	115
Provision for credit losses	2	(1)
Net charge-offs
Charge-offs	(1)	(2)
Recoveries	1	1
Net charge-offs		(1)
Ending balance	118	113
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning balance	629	631
Provision for credit losses	52	14
Net charge-offs
Charge-offs	(59)	(44)
Recoveries	13	13
Net charge-offs	(46)	(31)
Ending balance	$ 635	$ 614