Mortgage Banking Activities, Amortized Mortgage Servicing Rights (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Changes in amortized MSRs
Amortization	$ (65)	$ (79)	$ (127)	$ (143)
Amortized [Member]
Changes in amortized MSRs
Balance, beginning of period	1,252	1,219	1,242	1,229
Purchases	29	32	51	72
Servicing from securitizations or asset transfers	46	24	96	38
Amortization	(65)	(79)	(127)	(143)
Balance, end of period	1,262	1,196	1,262	1,196
Fair value of amortized MSRs:
Beginning of period	1,522	1,624	1,637	1,575
End of period	$ 1,692	$ 1,577	$ 1,692	$ 1,577