Investment Securities (Narrative) (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Investment Securities Disclosure [Abstract]
Gain on derivatives used to hedge purchase of investment securities	$ 93,000,000
Gross unrealized loss on debt securities held to maturity	74,000,000	$ 22,000,000
Gross unrealized loss on debt securities held to maturity in a continuous loss position for less than 12 months	51,000,000	1,000,000
Gross unrealized loss on debt securities held to maturity in a continuous loss position greater than 12 months	23,000,000	21,000,000
Gross unrealized loss on debt securities held to maturity in a continuous loss position for less than 12 months - fair value	4,000,000,000	134,000,000
Gross unrealized loss on debt securities held to maturity in a continuous loss position greater than 12 months - fair value	1,000,000,000	$ 1,600,000,000
Other Than Temporary Impairment Credit Losses Recognized In Earnings Credit Losses On Debt Securities Held	$ 1,200,000,000