Loans And Allowance For Credit Losses (Summary Of Past Due Loans (Accruing And Nonaccruing)) (Details) - USD ($) $ in Millions		Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans Receivable Held-for-sale, Net		$ 129	$ 93
Current		48,510	46,539
30-89 days past due		111	89
90+ days past due		88	86
Total past due		199	175
Loans and Leases Receivable, Gross		48,709	46,714
Accruing loans 90+ days past due		10	10
Nonaccrual loans that are current	[1]	129	145
Financing Receivable, Recorded Investment, Nonaccrual Status		243	246
loans held for sale [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		0	6
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Financing Receivable, Recorded Investment, Nonaccrual Status		175	152
Commercial Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		25,254	24,052
30-89 days past due		77	61
90+ days past due		57	49
Total past due		134	110
Loans and Leases Receivable, Gross		25,388	24,162
Accruing loans 90+ days past due		9	7
Nonaccrual loans that are current		98	96
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		5	1
Loans and Leases Receivable, Gross		2,211	2,186
Financing Receivable, Recorded Investment, Nonaccrual Status		16	38
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		9	10
Loans and Leases Receivable, Gross		2,917	2,937
Financing Receivable, Recorded Investment, Nonaccrual Status		12	13
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		1	1
Loans and Leases Receivable, Gross		155	180
Financing Receivable, Recorded Investment, Nonaccrual Status		0	0
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		95	68
Loans and Leases Receivable, Gross		14,760	14,513
Financing Receivable, Recorded Investment, Nonaccrual Status		110	82
Leasing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		0	2
Loans and Leases Receivable, Gross		334	327
Financing Receivable, Recorded Investment, Nonaccrual Status		0	2
Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		39	40
Loans and Leases Receivable, Gross		7,901	7,661
Financing Receivable, Recorded Investment, Nonaccrual Status		65	67
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		0	0
Loans and Leases Receivable, Gross		2,393	1,661
Financing Receivable, Recorded Investment, Nonaccrual Status		0	1
Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		11	15
Loans and Leases Receivable, Gross		9,344	8,939
Financing Receivable, Recorded Investment, Nonaccrual Status		16	38
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		11,539	11,109
30-89 days past due		13	5
90+ days past due		3	11
Total past due		16	16
Loans and Leases Receivable, Gross		11,555	11,125
Accruing loans 90+ days past due		0	1
Nonaccrual loans that are current		11	26
1-4 Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		36	33
Loans and Leases Receivable, Gross		7,568	7,176
Financing Receivable, Recorded Investment, Nonaccrual Status		40	42
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		0	1
Loans and Leases Receivable, Gross		624	643
Financing Receivable, Recorded Investment, Nonaccrual Status		0	0
Bankcard And Other Revolving Plans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total past due		3	4
Loans and Leases Receivable, Gross		502	491
Financing Receivable, Recorded Investment, Nonaccrual Status		0	1
Consumer Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		11,717	11,378
30-89 days past due		21	23
90+ days past due		28	26
Total past due		49	49
Loans and Leases Receivable, Gross		11,766	11,427
Accruing loans 90+ days past due		1	2
Nonaccrual loans that are current		20	23
Financing Receivable, Recorded Investment, Nonaccrual Status		52	56
Special Mention [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans and Leases Receivable, Gross		539	427
Revolving Credit Facility [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			487
30-89 days past due			2
90+ days past due			2
Accruing loans 90+ days past due			2
Revolving Credit Facility [Member] | Bankcard And Other Revolving Plans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		499
30-89 days past due		2
90+ days past due		1
Accruing loans 90+ days past due		1
Financing Receivable, Recorded Investment, Nonaccrual Status		0	0
loans held for sale [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		129	89
30-89 days past due		0	0
90+ days past due		0	4
Total past due		0	4
Loans and Leases Receivable, Gross		129	93
Accruing loans 90+ days past due		0	0
Financing Receivable, Recorded Investment, Nonaccrual Status		0	2
Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			2,185
30-89 days past due			1
90+ days past due			0
Accruing loans 90+ days past due			0
Commercial Real Estate [Member] | Commercial Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		2,206
30-89 days past due		5
90+ days past due		0
Accruing loans 90+ days past due		0
Financing Receivable, Recorded Investment, Nonaccrual Status		1	0
Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			2,927
30-89 days past due			4
90+ days past due			6
Accruing loans 90+ days past due			0
Home Equity Line of Credit [Member] | Home Equity Line of Credit [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		2,908
30-89 days past due		6
90+ days past due		3
Accruing loans 90+ days past due		0
Financing Receivable, Recorded Investment, Nonaccrual Status		7	4
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			179
30-89 days past due			1
90+ days past due			0
Accruing loans 90+ days past due			0
Consumer Portfolio Segment [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		154
30-89 days past due		1
90+ days past due		0
Accruing loans 90+ days past due		0
Financing Receivable, Recorded Investment, Nonaccrual Status		0	0
Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			14,445
30-89 days past due			37
90+ days past due			31
Accruing loans 90+ days past due			4
Commercial And Industrial [Member] | Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		14,665
30-89 days past due		57
90+ days past due		38
Accruing loans 90+ days past due		8
Financing Receivable, Recorded Investment, Nonaccrual Status		54	46
Leasing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			325
30-89 days past due			1
90+ days past due			1
Accruing loans 90+ days past due			0
Leasing [Member] | Leasing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		334
30-89 days past due		0
90+ days past due		0
Accruing loans 90+ days past due		1
Financing Receivable, Recorded Investment, Nonaccrual Status		0	1
Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			7,621
30-89 days past due			23
90+ days past due			17
Accruing loans 90+ days past due			3
Owner Occupied [Member] | Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		7,862
30-89 days past due		20
90+ days past due		19
Accruing loans 90+ days past due		0
Financing Receivable, Recorded Investment, Nonaccrual Status		44	48
Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			1,661
30-89 days past due			0
90+ days past due			0
Accruing loans 90+ days past due			0
Municipal [Member] | Municipal [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		2,393
30-89 days past due		0
90+ days past due		0
Accruing loans 90+ days past due		0
Financing Receivable, Recorded Investment, Nonaccrual Status		0	1
Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			8,924
30-89 days past due			4
90+ days past due			11
Accruing loans 90+ days past due			1
Term [Member] | Term [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		9,333
30-89 days past due		8
90+ days past due		3
Accruing loans 90+ days past due		0
Financing Receivable, Recorded Investment, Nonaccrual Status		10	26
1-4 Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			7,143
30-89 days past due			15
90+ days past due			18
Accruing loans 90+ days past due			0
1-4 Family Residential [Member] | 1-4 Family Residential [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		7,532
30-89 days past due		12
90+ days past due		24
Accruing loans 90+ days past due		0
Financing Receivable, Recorded Investment, Nonaccrual Status		13	19
Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current			642
30-89 days past due			1
90+ days past due			0
Accruing loans 90+ days past due			0
Construction And Other Consumer Real Estate [Member] | Construction And Other Consumer Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Current		624
30-89 days past due		0
90+ days past due		0
Accruing loans 90+ days past due		0
Financing Receivable, Recorded Investment, Nonaccrual Status		$ 0	$ 0

[1] Represents nonaccrual loans that are not past due more than 30 days; however, full payment of principal and interest is still not expected.