Mortgage Banking Activities, Mortgage Servicing Rights Carried at Fair Value (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Changes in MSRs measured at fair value
Fair value, beginning of period			$ 12,738
Changes in fair value:
Net changes in valuation model inputs or assumptions	$ 1,053	$ (835)	280	$ (1,276)
Other changes in fair value	(554)	(489)	(1,087)	(964)
Total changes in fair value	499	(1,324)	(807)	(2,240)
Fair value, end of period	12,661		12,661
Carried at fair value [Member]
Changes in MSRs measured at fair value
Fair value, beginning of period	11,739	14,953	12,738	15,580
Servicing from securitizations or asset transfers	428	271	736	560
Sales and other reductions	(5)	0	(6)	0
Net additions	423	271	730	560
Changes in fair value:
Net changes in valuation model inputs or assumptions	1,053	(835)	280	(1,276)
Other changes in fair value	(554)	(489)	(1,087)	(964)
Total changes in fair value	499	(1,324)	(807)	(2,240)
Fair value, end of period	12,661	13,900	12,661	13,900
Carried at fair value [Member] | Mortgage interest rates [Member]
Changes in fair value:
Net changes in valuation model inputs or assumptions	1,117	(876)	545	(1,385)
Carried at fair value [Member] | Servicing and foreclosure costs [Member]
Changes in fair value:
Net changes in valuation model inputs or assumptions	(10)	23	(28)	(11)
Carried at fair value [Member] | Discount Rates [Member]
Changes in fair value:
Net changes in valuation model inputs or assumptions	0	(55)	0	(55)
Carried at fair value [Member] | Prepayment estimates and other [Member]
Changes in fair value:
Net changes in valuation model inputs or assumptions	$ (54)	$ 73	$ (237)	$ 175