Purchased Loans (Purchase Loan Balances) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Purchased Impaired Loans - Outstanding Balance	$ 3,933	$ 5,007
Purchased Impaired Loans - Recorded Investment	3,522	4,858	$ 6,106
Purchased Impaired Loans - Carrying Value	3,212	3,986
Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Purchased Impaired Loans - Outstanding Balance	1,915	2,396
Total commercial lending [Member]
Financing Receivable, Impaired [Line Items]
Purchased Impaired Loans - Outstanding Balance	249	466
Purchased Impaired Loans - Recorded Investment	169	310	673
Purchased Impaired Loans - Carrying Value	120	231
Total commercial lending [Member] | Commercial [Member]
Financing Receivable, Impaired [Line Items]
Purchased Impaired Loans - Outstanding Balance	94	159
Purchased Impaired Loans - Recorded Investment	36	74
Purchased Impaired Loans - Carrying Value	24	57
Total commercial lending [Member] | Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Purchased Impaired Loans - Outstanding Balance	155	307
Purchased Impaired Loans - Recorded Investment	133	236
Purchased Impaired Loans - Carrying Value	96	174
Total consumer lending [Member]
Financing Receivable, Impaired [Line Items]
Purchased Impaired Loans - Outstanding Balance	3,684	4,541
Purchased Impaired Loans - Recorded Investment	3,353	4,548	$ 5,433
Purchased Impaired Loans - Carrying Value	3,092	3,755
Total consumer lending [Member] | Consumer [Member]
Financing Receivable, Impaired [Line Items]
Purchased Impaired Loans - Outstanding Balance	1,769	2,145
Purchased Impaired Loans - Recorded Investment	1,407	1,989
Purchased Impaired Loans - Carrying Value	1,392	1,661
Total consumer lending [Member] | Residential Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Purchased Impaired Loans - Outstanding Balance	1,915	2,396
Purchased Impaired Loans - Recorded Investment	1,946	2,559
Purchased Impaired Loans - Carrying Value	$ 1,700	$ 2,094