Commitments and Contingencies (Schedule of Commitments and Contingencies) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014
Commitments and Contingencies
Letters of credit and financial guarantees	$ 3,422	$ 3,462
Carrying amount of the liability for letter of credit guarantees	24	22
Carrying amount of investments in affordable housing projects	1,515	1,416
Amount of future funding commitments included in carrying amount of investments in affordable housing projects	536	459
Lending exposure related to investments in affordable housing projects	178	169
Tax credits subject to recapture related to investments in affordable housing projects	297	300
Amortization recognized in the provision for income taxes related to investments in affordable housing projects	46	161
Tax credits and other tax benefits recognized in the provision for income taxes related to investments in affordable housing projects	65	222
Investments in private equity and similar investments	366	329
Future funding commitments to consolidated private equity funds	$ 184	$ 202