Loan Sale and Servicing Activities and Variable Interest Entities (Principal Balance, Delinquent Loans (Loans 90 Days or More Past Due), and Net Charge-Offs Related to Serviced Loans) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Residential Mortgages [Member]
Total principal balance	$ 75,639,000,000		$ 75,639,000,000		$ 79,108,000,000
Delinquent loans	2,161,000,000		2,161,000,000		2,657,000,000
Net charge-offs	37,000,000	$ 34,000,000	69,000,000	$ 75,000,000
Commercial Mortgages [Member]
Total principal balance	56,552,000,000		56,552,000,000		60,873,000,000
Delinquent loans	672,000,000		672,000,000		707,000,000
Net charge-offs	148,000,000	345,000,000	255,000,000	700,000,000
Home Equity Loans Lines [Member]
Total principal balance	3,438,000,000		3,438,000,000		3,833,000,000
Delinquent loans	1,129,000,000		1,129,000,000		$ 1,303,000,000
Net charge-offs	$ 8,000,000	$ 15,000,000	$ 15,000,000	$ 32,000,000