Loans and Related Allowance for Credit Losses, Commercial Loan Categories by Risk Categories and Vintage (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 911,807	$ 895,394	$ 861,572
Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	38,166	119,666
Term loans by origination year, fiscal year before current fiscal year	101,094	40,707
Term loans by origination year, two years before current fiscal year	40,387	51,742
Term loans by origination year, three years before current fiscal year	48,374	27,066
Term loans by origination year, four years before current fiscal year	24,925	14,179
Term loans by origination year, more than five years before current fiscal year	40,453	35,226
Revolving loans	232,660	223,833
Revolving loans converted to term loans	655	701
Loans	526,714	513,120
Total Commercial [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	501,200
Total Commercial [Member] | Criticized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	25,500
Commercial and industrial loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	26,284	67,219
Term loans by origination year, fiscal year before current fiscal year	50,611	16,077
Term loans by origination year, two years before current fiscal year	16,903	21,790
Term loans by origination year, three years before current fiscal year	20,747	8,656
Term loans by origination year, four years before current fiscal year	7,877	4,482
Term loans by origination year, more than five years before current fiscal year	12,697	14,536
Revolving loans	226,364	216,980
Revolving loans converted to term loans	654	696
Loans	362,137	350,436
Commercial and industrial loans [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	25,954	65,562
Term loans by origination year, fiscal year before current fiscal year	49,141	15,193
Term loans by origination year, two years before current fiscal year	16,084	20,553
Term loans by origination year, three years before current fiscal year	19,801	7,400
Term loans by origination year, four years before current fiscal year	6,756	3,797
Term loans by origination year, more than five years before current fiscal year	11,769	13,985
Revolving loans	221,270	211,452
Revolving loans converted to term loans	643	679
Loans	351,418	338,621
Commercial and industrial loans [Member] | Criticized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	330	1,657
Term loans by origination year, fiscal year before current fiscal year	1,470	884
Term loans by origination year, two years before current fiscal year	819	1,237
Term loans by origination year, three years before current fiscal year	946	1,256
Term loans by origination year, four years before current fiscal year	1,121	685
Term loans by origination year, more than five years before current fiscal year	928	551
Revolving loans	5,094	5,528
Revolving loans converted to term loans	11	17
Loans	10,719	11,815
Real estate mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	10,086	41,658
Term loans by origination year, fiscal year before current fiscal year	39,326	17,048
Term loans by origination year, two years before current fiscal year	16,419	21,988
Term loans by origination year, three years before current fiscal year	20,383	14,452
Term loans by origination year, four years before current fiscal year	13,409	8,326
Term loans by origination year, more than five years before current fiscal year	24,619	18,447
Revolving loans	5,253	5,811
Revolving loans converted to term loans	0	3
Loans	129,495	127,733
Real estate mortgage [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	9,636	38,196
Term loans by origination year, fiscal year before current fiscal year	36,066	15,929
Term loans by origination year, two years before current fiscal year	15,336	19,013
Term loans by origination year, three years before current fiscal year	17,767	12,618
Term loans by origination year, four years before current fiscal year	11,912	7,451
Term loans by origination year, more than five years before current fiscal year	21,815	16,026
Revolving loans	5,009	5,411
Revolving loans converted to term loans	0	3
Loans	117,541	114,647
Real estate mortgage [Member] | Criticized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	450	3,462
Term loans by origination year, fiscal year before current fiscal year	3,260	1,119
Term loans by origination year, two years before current fiscal year	1,083	2,975
Term loans by origination year, three years before current fiscal year	2,616	1,834
Term loans by origination year, four years before current fiscal year	1,497	875
Term loans by origination year, more than five years before current fiscal year	2,804	2,421
Revolving loans	244	400
Revolving loans converted to term loans	0	0
Loans	11,954	13,086
Real estate construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	1,108	6,405
Term loans by origination year, fiscal year before current fiscal year	6,730	4,324
Term loans by origination year, two years before current fiscal year	4,071	5,135
Term loans by origination year, three years before current fiscal year	4,750	2,401
Term loans by origination year, four years before current fiscal year	2,282	447
Term loans by origination year, more than five years before current fiscal year	628	336
Revolving loans	1,043	1,042
Revolving loans converted to term loans	1	2
Loans	20,613	20,092
Real estate construction [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	913	5,895
Term loans by origination year, fiscal year before current fiscal year	6,255	4,058
Term loans by origination year, two years before current fiscal year	3,866	4,549
Term loans by origination year, three years before current fiscal year	4,216	2,167
Term loans by origination year, four years before current fiscal year	2,055	379
Term loans by origination year, more than five years before current fiscal year	561	329
Revolving loans	1,043	1,042
Revolving loans converted to term loans	1	2
Loans	18,910	18,421
Real estate construction [Member] | Criticized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	195	510
Term loans by origination year, fiscal year before current fiscal year	475	266
Term loans by origination year, two years before current fiscal year	205	586
Term loans by origination year, three years before current fiscal year	534	234
Term loans by origination year, four years before current fiscal year	227	68
Term loans by origination year, more than five years before current fiscal year	67	7
Revolving loans	0	0
Revolving loans converted to term loans	0	0
Loans	1,703	1,671
Lease financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	688	4,384
Term loans by origination year, fiscal year before current fiscal year	4,427	3,258
Term loans by origination year, two years before current fiscal year	2,994	2,829
Term loans by origination year, three years before current fiscal year	2,494	1,557
Term loans by origination year, four years before current fiscal year	1,357	924
Term loans by origination year, more than five years before current fiscal year	2,509	1,907
Revolving loans	0	0
Revolving loans converted to term loans	0	0
Loans	14,469	14,859
Lease financing [Member] | Pass [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	611	4,100
Term loans by origination year, fiscal year before current fiscal year	4,152	3,012
Term loans by origination year, two years before current fiscal year	2,777	2,547
Term loans by origination year, three years before current fiscal year	2,245	1,373
Term loans by origination year, four years before current fiscal year	1,203	838
Term loans by origination year, more than five years before current fiscal year	2,361	1,805
Revolving loans	0	0
Revolving loans converted to term loans	0	0
Loans	13,349	13,675
Lease financing [Member] | Criticized [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Term loans by origination year, current fiscal year	77	284
Term loans by origination year, fiscal year before current fiscal year	275	246
Term loans by origination year, two years before current fiscal year	217	282
Term loans by origination year, three years before current fiscal year	249	184
Term loans by origination year, four years before current fiscal year	154	86
Term loans by origination year, more than five years before current fiscal year	148	102
Revolving loans	0	0
Revolving loans converted to term loans	0	0
Loans	$ 1,120	$ 1,184