Securities (Details 5) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Securities held to maturity
Securities held to maturity, Amortized Cost	$ 8,329	$ 6,671
Securities held to maturity, Gross Unrealized Gains, Recognized in Other Comprehensive Income (OCI)	6	7
Securities held to maturity, gross unrealized losses, recognized in other comprehensive income (OCI)	158	169
Total securities held to maturity, carrying amount	8,177	6,509
Securities held to maturity, Gross Unrealized Gains, Not Recognized in OCI	93	11
Securities held to maturity, Gross Unrealized Losses, Not Recognized in OCI	19	81
Total securities held to maturity, Fair Value	8,251	6,439
Residential mortgage-backed securities, U.S. government agency and government-sponsored agencies
Securities held to maturity
Securities held to maturity, Amortized Cost	5,734	5,065
Securities held to maturity, Gross Unrealized Gains, Recognized in Other Comprehensive Income (OCI)	6	7
Securities held to maturity, gross unrealized losses, recognized in other comprehensive income (OCI)	71	77
Total securities held to maturity, carrying amount	5,669	4,995
Securities held to maturity, Gross Unrealized Gains, Not Recognized in OCI	42	8
Securities held to maturity, Gross Unrealized Losses, Not Recognized in OCI	13	69
Total securities held to maturity, Fair Value	5,698	4,934
U.S. government agency and government-sponsored agencies - commercial mortgage-backed securities
Securities held to maturity
Securities held to maturity, Amortized Cost	1,836	1,606
Securities held to maturity, gross unrealized losses, recognized in other comprehensive income (OCI)	87	92
Total securities held to maturity, carrying amount	1,749	1,514
Securities held to maturity, Gross Unrealized Gains, Not Recognized in OCI	48	3
Securities held to maturity, Gross Unrealized Losses, Not Recognized in OCI	5	12
Total securities held to maturity, Fair Value	1,792	1,505
U.S. Treasury
Securities held to maturity
Securities held to maturity, Amortized Cost	484
Total securities held to maturity, carrying amount	484
Securities held to maturity, Gross Unrealized Gains, Not Recognized in OCI	2
Total securities held to maturity, Fair Value	486
U.S. government sponsored agencies
Securities held to maturity
Securities held to maturity, Amortized Cost	275
Total securities held to maturity, carrying amount	275
Securities held to maturity, Gross Unrealized Gains, Not Recognized in OCI	1
Securities held to maturity, Gross Unrealized Losses, Not Recognized in OCI	1
Total securities held to maturity, Fair Value	$ 275