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 ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Derivatives Recognized in Income	$ 253	$ 105
Gain (Loss) on Related Hedged Items Recognized in Income	(274)	(118)
The ineffective portion of the change in value of our fair value hedge derivatives	(21)	(13)
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	(154)	(52)
Gain (Loss) on Related Hedged Items Recognized in Income	158	54
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	407	157
Gain (Loss) on Related Hedged Items Recognized in Income	$ (432)	$ (172)