Investment Securities - Additional Information (Details) $ in Millions	Sep. 30, 2015 USD ($) Security	Dec. 31, 2014 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Number of sale securities exceeding amortized cost over fair value \| Security	430
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (130)	$ (237)
Difference in amortized cost and fair value of securities that had been in a loss position for 12 months or longer	$ (94)	(206)
Securities held to maturity \| Security	30
Fair value of securities pledged	$ 2,100	3,500
Carrying value of securities pledged	8,700	9,000
Encumbered amount of securities pledged as collateral	10,400	10,600
Fair value of securities pledged, accepted	231	91
Held-to-maturity Securities, Accumulated Unrecognized Holding Loss	$ (18)	$ (6)
Non-agency RMBS and CMBS, Non-agency ABS and Other Securities \| Gross Unrealized Losses on Available-for-sale Securities
Schedule of Available-for-sale Securities [Line Items]
Percentage of portfolio	20.00%
Investment Securities Portfolio \| US Treasury and Government
Schedule of Available-for-sale Securities [Line Items]
Percentage of portfolio	90.00%	86.00%
Non-agency RMBS and CMBS, Non-agency ABS and Other Securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Accumulated Loss	$ (26)

Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer.

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Amount of obligation to return securities collateral under master netting arrangements that have not been offset against derivative assets.

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Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale that are pledged to one or more secured parties who have the right to buy, sell, or re-pledge the collateral.

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