Loans and Allowance for Credit Losses, Significant Activity (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Loans and Allowance for Credit Losses, Significant Activity [Abstract]
Purchases	$ 10,050	$ 1,523	$ 11,141	$ 2,705
Sales	(158)	(1,983)	(393)	(3,674)
Transfers to MHFS/LHFS	(50)	(9,797)	(59)	(9,837)
Consumer Real Estate Loans Government Guaranteed Or Insured [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing Receivable Certain Purchases Net Of Certain Transfers To Held For Sale	(228)	(1,300)	900	237
Commercial Portfolio Segment [Member]
Loans and Allowance for Credit Losses, Significant Activity [Abstract]
Purchases	9,739	1,523	10,830	2,537
Sales	(157)	(1,958)	(363)	(3,599)
Transfers to MHFS/LHFS	(45)	(24)	(52)	(59)
Consumer Portfolio Segment [Member]
Loans and Allowance for Credit Losses, Significant Activity [Abstract]
Purchases	311	0	311	168
Sales	(1)	(25)	(30)	(75)
Transfers to MHFS/LHFS	$ (5)	$ (9,773)	$ (7)	$ (9,778)