Securities (Details 3) $ in Millions	Sep. 30, 2015 USD ($)
Securities available for sale
One Year or Less	$ 70
Over One Year Through Five Years	526
Over Five Years Through Ten Years	2,525
Over Ten Years	11,226
Total Fair Value	14,347
Residential mortgage-backed securities, U.S. government agency and government-sponsored agencies
Securities available for sale
One Year or Less	0
Over One Year Through Five Years	22
Over Five Years Through Ten Years	382
Over Ten Years	7,456
Total Fair Value	7,860
Residential mortgage-backed securities, Privately issued
Securities available for sale
One Year or Less	0
Over One Year Through Five Years	3
Over Five Years Through Ten Years	0
Over Ten Years	129
Total Fair Value	132
Privately issued - commercial mortgage-backed securities
Securities available for sale
One Year or Less	0
Over One Year Through Five Years	0
Over Five Years Through Ten Years	37
Over Ten Years	1,558
Total Fair Value	1,595
Collateralized loan obligations
Securities available for sale
One Year or Less	0
Over One Year Through Five Years	11
Over Five Years Through Ten Years	1,444
Over Ten Years	1,654
Total Fair Value	3,109
Other Asset Liability Management Securities
Securities available for sale
One Year or Less	0
Over One Year Through Five Years	2
Over Five Years Through Ten Years	6
Over Ten Years	0
Total Fair Value	8
Asset Liability Management securities
Securities available for sale
One Year or Less	0
Over One Year Through Five Years	38
Over Five Years Through Ten Years	1,869
Over Ten Years	10,797
Total Fair Value	12,704
Other debt securities, Direct bank purchase bonds
Securities available for sale
One Year or Less	66
Over One Year Through Five Years	476
Over Five Years Through Ten Years	654
Over Ten Years	398
Total Fair Value	1,594
Other debt securities, Other
Securities available for sale
One Year or Less	4
Over One Year Through Five Years	12
Over Five Years Through Ten Years	2
Over Ten Years	31
Total Fair Value	$ 49