Derivative Instruments and Hedging Activities - Offsetting Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Derivatives liabilities(1)(2)
Derivative Liabilities, Gross Amount	$ 1,531	$ 1,438
Derivative Liability, Offsetting Financial Instruments	(194)	(152)
Derivative Liability, Offsetting Cash Collateral	(52)	(184)
Derivative Liability	1,285	1,102
Derivative Liability, Securities Collateral Not Netted	0	0
Net Exposure	1,285	1,102
Derivative Liability, Not Subject to Master Netting Arrangement	1,000	908
Repurchase agreements(3)(4)
Gross Amounts	1,046	992
Securities Sold under Agreements to Repurchase, Asset	0	0
Repurchase Agreement, Collateral, Right To Reclaim Cash, Offset	0	0
Net Amounts as Recognized	1,046	992
Offsetting Amounts Not Netted, Collateral Pledged	(1,046)	(992)
Net Exposure	0	0
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	1,100
Derivative, Collateral, Obligation to Return Cash	208	448
Derivative, Collateral, Obligation to Return Securities	1	16
Derivative, Collateral, Right to Reclaim Cash	$ 1,400	$ 1,500