Loans and Allowance for Credit Losses, Significant Activity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Loans and Allowance for Credit Losses, Significant Activity [Abstract]
Purchases	$ 1,214	$ 6,226	$ 3,919	$ 9,955
Sales	(1,310)	(1,201)	(4,984)	(5,459)
Transfers to MHFS/LHFS	(12)	(68)	(9,849)	(213)
Commercial Portfolio Segment [Member]
Loans and Allowance for Credit Losses, Significant Activity [Abstract]
Purchases	1,214	6,226	3,751	9,374
Sales	(1,270)	(1,177)	(4,869)	(4,989)
Transfers to MHFS/LHFS	(14)	(65)	(73)	(198)
Consumer Portfolio Segment [Member]
Loans and Allowance for Credit Losses, Significant Activity [Abstract]
Purchases	0	0	168	581
Sales	(40)	(24)	(115)	(470)
Transfers to MHFS/LHFS	$ 2	$ (3)	$ (9,776)	$ (15)