Derivative Instruments and Hedging Activities - Offsetting Assets (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative, Collateral, Obligation to Return Cash	$ 448	$ 544
Derivatives assets(1)(2)
Gross Amounts	1,494	1,518
Derivative Asset, Offsetting Financial Instruments	(152)	(86)
Derivative Assets, Offsetting Cash Collateral	(387)	(446)
Derivative Assets	955	986
Derivative Asset, Securities Not Netted	(11)	(156)
Net Exposure	944	830
Derivative Asset, Not Subject to Master Netting Arrangement	491	429
Derivative, Collateral, Obligation to Return Securities	16	172
Derivative, Collateral, Right to Reclaim Cash	$ 1,500	$ 304