Financial Derivatives (Gains (Losses) on Derivatives and Related Hedged Items - Fair Value Hedges) (Details) - Fair Value Hedging [Member] - Designated as Hedging Instrument [Member] - Interest Rate Contracts [Member] - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives Recognized in Income	$ (108,000,000)	$ 12,000,000	$ (633,000,000)
Gain (Loss) on Related Hedged Items Recognized in Income	67,000,000	(42,000,000)	596,000,000
The ineffective portion of the change in value of our fair value hedge derivatives	(41,000,000)	(30,000,000)	(37,000,000)
Us Treasury And Government And Other Debt Securities [Member] | Investment Securities Interest Income [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives Recognized in Income		(111,000,000)	111,000,000
Gain (Loss) on Related Hedged Items Recognized in Income		116,000,000	(115,000,000)
Subordinated debt and Bank notes and senior debt [Member] | Borrowed Funds Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives Recognized in Income	(108,000,000)	123,000,000	(744,000,000)
Gain (Loss) on Related Hedged Items Recognized in Income	$ 67,000,000	$ (158,000,000)	$ 711,000,000