Derivative Instruments and Other Financial Instruments Used For Hedging - Amount of Net Gains (Losses) for Derivatives Classified as Trading (Details) - Trading Derivatives - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Trading Derivatives
Gain or (Loss) Recognized in Income on Derivative Instruments	$ 47	$ 67
Interest rate contracts
Trading Derivatives
Gain or (Loss) Recognized in Income on Derivative Instruments	17	36
Equity contracts
Trading Derivatives
Gain or (Loss) Recognized in Income on Derivative Instruments	0	3
Foreign exchange contracts
Trading Derivatives
Gain or (Loss) Recognized in Income on Derivative Instruments	27	19
Commodity contracts
Trading Derivatives
Gain or (Loss) Recognized in Income on Derivative Instruments	3	8
Other contracts
Trading Derivatives
Gain or (Loss) Recognized in Income on Derivative Instruments	$ 0	$ 1