Allowances for Loan and Lease Losses (Rollforward of Allowance For Loan and Lease Losses and Associated Loan Data) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	$ 2,589,000,000		$ 2,727,000,000		$ 3,331,000,000
Charge-offs	(786,000,000)		(886,000,000)		(805,000,000)
Recoveries	329,000,000		343,000,000		419,000,000
Net charge-offs	(457,000,000)		(543,000,000)		(386,000,000)
Provision for credit losses	441,000,000		433,000,000		255,000,000
Net (increase) / decrease in allowance for unfunded loan commitments and letters of credit	4,000,000		(40,000,000)		(2,000,000)
Other	34,000,000		12,000,000		(471,000,000)
Ending Balance	2,611,000,000		2,589,000,000		2,727,000,000
Loans collectively evaluated for impairment - associated allowance	2,067,000,000		1,938,000,000		2,022,000,000
Impaired loans - associated allowance	271,000,000		331,000,000
Loans collectively evaluated for impairment	214,822,000,000		204,392,000,000		199,609,000,000
Fair value option loans	869,000,000		893,000,000		905,000,000
Purchased impaired loans	2,396,000,000		2,956,000,000		3,522,000,000
Total Loans	$ 220,458,000,000	[1]	$ 210,833,000,000	[1]	$ 206,696,000,000
Portfolio segment ALLL as a percentage of total ALLL	100.00%		100.00%		100.00%
Ratio of the allowance for loan and lease losses to total loans	1.18%		1.23%		1.32%
Loans Accounted for under Fair Value Option
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans collectively evaluated for impairment - associated allowance	$ 0		$ 0		$ 0
TDRs
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	230,000,000		271,000,000		319,000,000
Loans individually evaluated for impairment	2,061,000,000		2,221,000,000		2,351,000,000
Other Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	41,000,000		60,000,000		76,000,000
Loans individually evaluated for impairment	310,000,000		371,000,000		309,000,000
Purchased Impaired Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired loans - associated allowance	273,000,000		320,000,000		310,000,000
Total commercial lending
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	1,534,000,000		1,605,000,000		1,571,000,000
Charge-offs	(221,000,000)		(363,000,000)		(255,000,000)
Recoveries	116,000,000		178,000,000		240,000,000
Net charge-offs	(105,000,000)		(185,000,000)		(15,000,000)
Provision for credit losses	147,000,000		153,000,000		55,000,000
Net (increase) / decrease in allowance for unfunded loan commitments and letters of credit	5,000,000		(39,000,000)		(3,000,000)
Other	1,000,000				(3,000,000)
Ending Balance	1,582,000,000		1,534,000,000		1,605,000,000
Loans collectively evaluated for impairment - associated allowance	1,506,000,000		1,392,000,000		1,437,000,000
Impaired loans - associated allowance	76,000,000		105,000,000
Loans collectively evaluated for impairment	146,720,000,000		137,047,000,000		132,632,000,000
Purchased impaired loans			109,000,000		169,000,000
Total Loans	$ 147,439,000,000		$ 137,955,000,000		$ 133,544,000,000
Portfolio segment ALLL as a percentage of total ALLL	61.00%		59.00%		59.00%
Ratio of the allowance for loan and lease losses to total loans	1.07%		1.11%		1.20%
Total commercial lending | TDRs
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	$ 35,000,000		$ 45,000,000		$ 43,000,000
Loans individually evaluated for impairment	409,000,000		428,000,000		434,000,000
Total commercial lending | Other Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	41,000,000		60,000,000		76,000,000
Loans individually evaluated for impairment	310,000,000		371,000,000		309,000,000
Total commercial lending | Purchased Impaired Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Impaired loans - associated allowance			37,000,000		49,000,000
Total consumer lending
Financing Receivable, Allowance for Credit Losses [Line Items]
Beginning Balance	1,055,000,000		1,122,000,000		1,760,000,000
Charge-offs	(565,000,000)		(523,000,000)		(550,000,000)
Recoveries	213,000,000		165,000,000		179,000,000
Net charge-offs	(352,000,000)		(358,000,000)		(371,000,000)
Provision for credit losses	294,000,000		280,000,000		200,000,000
Net (increase) / decrease in allowance for unfunded loan commitments and letters of credit	(1,000,000)		(1,000,000)		1,000,000
Other	33,000,000		12,000,000		(468,000,000)
Ending Balance	1,029,000,000		1,055,000,000		1,122,000,000
Loans collectively evaluated for impairment - associated allowance	561,000,000		546,000,000		585,000,000
Impaired loans - associated allowance	195,000,000		226,000,000
Loans collectively evaluated for impairment	68,102,000,000		67,345,000,000		66,977,000,000
Fair value option loans	869,000,000		893,000,000		905,000,000
Purchased impaired loans	2,396,000,000		2,847,000,000		3,353,000,000
Total Loans	$ 73,019,000,000		$ 72,878,000,000		$ 73,152,000,000
Portfolio segment ALLL as a percentage of total ALLL	39.00%		41.00%		41.00%
Ratio of the allowance for loan and lease losses to total loans	1.41%		1.45%		1.53%
Total consumer lending | TDRs
Financing Receivable, Allowance for Credit Losses [Line Items]
Loans individually evaluated for impairment - associated allowance	$ 195,000,000		$ 226,000,000		$ 276,000,000
Loans individually evaluated for impairment	1,652,000,000		1,793,000,000		1,917,000,000
Total consumer lending | Purchased Impaired Loans
Financing Receivable, Allowance for Credit Losses [Line Items]
Net charge-offs					(468,000,000)
Impaired loans - associated allowance	$ 273,000,000		$ 283,000,000		$ 261,000,000

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $1.7 billion, Loans of $.9 billion, and Other assets of $.3 billion at December 31, 2017 and Loans held for sale of $2.4 billion, Loans of $.9 billion, and Other assets of $.5 billion at December 31, 2016.