Loans and Leases - Balances Of Commercial Loan Portfolio Classes, Disaggregated By PD Grade (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	$ 55,012	$ 54,859
Commercial and industrial | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	1,468	7,421
Financing receivable, originated year two	7,070	3,676
Financing receivable, originated year three	3,658	3,556
Financing receivable, originated year four	2,848	1,606
Financing receivable, originated year five	1,181	1,253
Financing receivable, originated prior to year five	2,364	2,358
LMC, Non-Revolving Loans	3,895	4,518
Revolving Loans	8,251	6,615
Revolving Loans converted to term loans	63	65
Loans and leases	30,798	31,068
Revolving loans converted to term loan during period	0	0
Commercial and industrial | PD Grade 1 -12 | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	1,445	7,372
Financing receivable, originated year two	6,983	3,576
Financing receivable, originated year three	3,529	3,439
Financing receivable, originated year four	2,764	1,455
Financing receivable, originated year five	1,045	1,193
Financing receivable, originated prior to year five	2,278	2,267
LMC, Non-Revolving Loans	3,895	4,518
Revolving Loans	8,047	6,386
Revolving Loans converted to term loans	12	13
Loans and leases	29,998	30,219
Commercial and industrial | PD Grade 13 | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	2	25
Financing receivable, originated year two	53	39
Financing receivable, originated year three	57	50
Financing receivable, originated year four	36	48
Financing receivable, originated year five	37	36
Financing receivable, originated prior to year five	45	43
LMC, Non-Revolving Loans	0	0
Revolving Loans	92	100
Revolving Loans converted to term loans	0	4
Loans and leases	322	345
Commercial and industrial | PD Grade 14 ,15 and 16 | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	21	24
Financing receivable, originated year two	34	61
Financing receivable, originated year three	72	67
Financing receivable, originated year four	48	103
Financing receivable, originated year five	99	24
Financing receivable, originated prior to year five	41	48
LMC, Non-Revolving Loans	0	0
Revolving Loans	112	129
Revolving Loans converted to term loans	51	48
Loans and leases	478	504
Commercial real estate | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and leases	12,487	12,109
Commercial real estate | CRE | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	1,250	3,492
Financing receivable, originated year two	4,079	2,091
Financing receivable, originated year three	2,995	2,590
Financing receivable, originated year four	2,220	1,057
Financing receivable, originated year five	540	744
Financing receivable, originated prior to year five	1,128	1,919
Revolving Loans	275	216
Revolving Loans converted to term loans	0	0
Loans and leases	12,487	12,109
Commercial real estate | PD Grade 1 -12 | CRE | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	1,224	3,441
Financing receivable, originated year two	3,975	2,065
Financing receivable, originated year three	2,837	2,514
Financing receivable, originated year four	2,180	929
Financing receivable, originated year five	538	691
Financing receivable, originated prior to year five	1,085	1,822
Revolving Loans	264	204
Revolving Loans converted to term loans	0	0
Loans and leases	12,103	11,666
Commercial real estate | PD Grade 13 | CRE | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	25	4
Financing receivable, originated year two	15	26
Financing receivable, originated year three	134	52
Financing receivable, originated year four	25	125
Financing receivable, originated year five	0	20
Financing receivable, originated prior to year five	18	65
Revolving Loans	0	0
Revolving Loans converted to term loans	0	0
Loans and leases	217	292
Commercial real estate | PD Grade 14 ,15 and 16 | CRE | Commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, originated year one	1	47
Financing receivable, originated year two	89	0
Financing receivable, originated year three	24	24
Financing receivable, originated year four	15	3
Financing receivable, originated year five	2	33
Financing receivable, originated prior to year five	25	32
Revolving Loans	11	12
Revolving Loans converted to term loans	0	0
Loans and leases	$ 167	$ 151