Securities (Details 7) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Securities held to maturity
Over One Year Through Five Years, Carrying Amount	$ 927
Over One Year Through Five Years, Fair Value	949
Over Five Years Through Ten Years, Carrying Amount	838
Over Five Years Through Ten Years, Fair Value	854
Over Ten Years, Carrying Amount	8,608
Over Ten Years, Fair Value	8,573
Total securities held to maturity, carrying amount	10,373	$ 10,337
Total securities held to maturity, Fair Value	10,376	10,316
U.S. Treasury securities
Securities held to maturity
Over One Year Through Five Years, Carrying Amount	494
Over One Year Through Five Years, Fair Value	497
Over Five Years Through Ten Years, Carrying Amount	0
Over Five Years Through Ten Years, Fair Value	0
Over Ten Years, Carrying Amount	0
Over Ten Years, Fair Value	0
Total securities held to maturity, carrying amount	494	492
Total securities held to maturity, Fair Value	497	497
Residential mortgage-backed securities, U.S. government agency and government-sponsored agencies
Securities held to maturity
Over One Year Through Five Years, Carrying Amount	0
Over One Year Through Five Years, Fair Value	0
Over Five Years Through Ten Years, Carrying Amount	417
Over Five Years Through Ten Years, Fair Value	414
Over Ten Years, Carrying Amount	7,907
Over Ten Years, Fair Value	7,868
Total securities held to maturity, carrying amount	8,324	8,263
Total securities held to maturity, Fair Value	8,282	$ 8,201
U.S. government agency and government-sponsored agencies - commercial mortgage-backed securities
Securities held to maturity
Over One Year Through Five Years, Carrying Amount	433
Over One Year Through Five Years, Fair Value	452
Over Five Years Through Ten Years, Carrying Amount	421
Over Five Years Through Ten Years, Fair Value	440
Over Ten Years, Carrying Amount	701
Over Ten Years, Fair Value	705
Total securities held to maturity, carrying amount	1,555
Total securities held to maturity, Fair Value	$ 1,597

Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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