Allowances for Loan and Lease Losses (Rollforward of Allowance For Loan and Lease Losses and Associated Loan Data) (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) segment		Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Financing Receivable, Allowance for Credit Losses [Line Items]
Number of portfolio segments | segment	2
Beginning Balance	$ 2,611,000,000		$ 2,589,000,000
Charge-offs	(193,000,000)		(198,000,000)
Recoveries	80,000,000		80,000,000
Net (charge-offs)	(113,000,000)		(118,000,000)
Provision for credit losses	92,000,000		88,000,000
Net (increase) / decrease in allowance for unfunded loan commitments and letters of credit	7,000,000		(4,000,000)
Other	7,000,000		6,000,000
Ending Balance	2,604,000,000		2,561,000,000
Loans collectively evaluated for impairment - associated allowance	2,069,000,000		1,938,000,000
Impaired loans - associated allowance	253,000,000			$ 271,000,000
Loans collectively evaluated for impairment	216,182,000,000		206,660,000,000
Fair value option loans	813,000,000		874,000,000
Purchased impaired loans	2,314,000,000		2,811,000,000
Total loans	$ 221,614,000,000	[1]	$ 212,826,000,000	220,458,000,000	[1]
Portfolio segment ALLL as a percentage of total ALLL	100.00%		100.00%
Ratio of the allowance for loan and lease losses to total loans	1.18%		1.20%
Loans Accounted for under Fair Value Option [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans collectively evaluated for impairment - associated allowance	$ 0
Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	67,000,000		$ 53,000,000
Loans individually evaluated for impairment	313,000,000		351,000,000
TDRs [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	186,000,000		252,000,000
Loans individually evaluated for impairment	1,992,000,000		2,130,000,000
Purchased Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired loans - associated allowance	282,000,000		318,000,000
Total commercial lending [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	1,582,000,000		1,534,000,000
Charge-offs	(36,000,000)		(55,000,000)
Recoveries	26,000,000		32,000,000
Net (charge-offs)	(10,000,000)		(23,000,000)
Provision for credit losses	37,000,000		23,000,000
Net (increase) / decrease in allowance for unfunded loan commitments and letters of credit	5,000,000		(5,000,000)
Other			1,000,000
Ending Balance	1,614,000,000		1,530,000,000
Loans collectively evaluated for impairment - associated allowance	1,513,000,000		1,412,000,000
Impaired loans - associated allowance	101,000,000			76,000,000
Loans collectively evaluated for impairment	148,248,000,000		139,863,000,000
Purchased impaired loans			82,000,000
Total loans	$ 148,945,000,000		$ 140,662,000,000	147,439,000,000
Portfolio segment ALLL as a percentage of total ALLL	62.00%		60.00%
Ratio of the allowance for loan and lease losses to total loans	1.08%		1.09%
Total commercial lending [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	$ 67,000,000		$ 53,000,000
Loans individually evaluated for impairment	313,000,000		351,000,000
Total commercial lending [Member] | TDRs [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	34,000,000		37,000,000
Loans individually evaluated for impairment	384,000,000		366,000,000
Total commercial lending [Member] | Purchased Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired loans - associated allowance			28,000,000
Total consumer lending [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	1,029,000,000		1,055,000,000
Charge-offs	(157,000,000)		(143,000,000)
Recoveries	54,000,000		48,000,000
Net (charge-offs)	(103,000,000)		(95,000,000)
Provision for credit losses	55,000,000		65,000,000
Net (increase) / decrease in allowance for unfunded loan commitments and letters of credit	2,000,000		1,000,000
Other	7,000,000		5,000,000
Ending Balance	990,000,000		1,031,000,000
Loans collectively evaluated for impairment - associated allowance	556,000,000		526,000,000
Impaired loans - associated allowance	152,000,000			195,000,000
Loans collectively evaluated for impairment	67,934,000,000		66,797,000,000
Fair value option loans	813,000,000		874,000,000
Purchased impaired loans	2,314,000,000		2,729,000,000
Total loans	$ 72,669,000,000		$ 72,164,000,000	$ 73,019,000,000
Portfolio segment ALLL as a percentage of total ALLL	38.00%		40.00%
Ratio of the allowance for loan and lease losses to total loans	1.36%		1.43%
Total consumer lending [Member] | TDRs [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	$ 152,000,000		$ 215,000,000
Loans individually evaluated for impairment	1,608,000,000		1,764,000,000
Total consumer lending [Member] | Purchased Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired loans - associated allowance	$ 282,000,000		$ 290,000,000

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $.9 billion, Loans of $.8 billion and Other assets of $.3 billion at March 31, 2018 and Loans held for sale of $1.7 billion, Loans of $.9 billion and Other assets of $.3 billion at December 31, 2017.