Derivative Instruments and Hedging Activities - Offsetting Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Derivatives liabilities(1)(2)
Derivative Liabilities, Gross Amount	$ 1,438	$ 520
Derivative Liability, Offsetting Financial Instruments	(152)	(86)
Derivative Liability, Offsetting Cash Collateral	(184)	(57)
Derivative Liability	1,102	377
Derivative Liability, Securities Collateral Not Netted	0	0
Net Exposure	1,102	377
Derivative Liability, Not Subject to Master Netting Arrangement	908	314
Repurchase agreements(3)(4)
Gross Amounts	992	969
Securities Sold under Agreements to Repurchase, Asset	0	0
Repurchase Agreement, Collateral, Right To Reclaim Cash, Offset	0	0
Net Amounts as Recognized	992	969
Offsetting Amounts Not Netted, Collateral Pledged	(992)	(969)
Net Exposure	0	0
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	1,000
Derivative, Collateral, Obligation to Return Cash	448	544
Derivative, Collateral, Obligation to Return Securities	16	172
Derivative, Collateral, Right to Reclaim Cash	$ 1,500	$ 304