Derivative Instruments and Hedging Activities - Offsetting Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Derivatives liabilities(1)
Derivative Liabilities, Gross Amount	$ 472	$ 339
Derivative Liability, Offsetting Financial Instruments	(84)	(101)
Derivative Liability, Offsetting Cash Collateral	(97)	(63)
Derivative Liability	291	175
Derivative Liability, Securities Collateral Not Netted	0	0
Net Exposure	291	175
Derivative Liability, Not Subject to Master Netting Arrangement	242	127
Repurchase agreements(2)(3)
Gross Amounts	1,012	869
Securities Sold under Agreements to Repurchase, Asset	0	0
Repurchase Agreement, Collateral, Right To Reclaim Cash, Offset	0	0
Net Amounts as Recognized	1,012	869
Offsetting Amounts Not Netted, Collateral Pledged	(1,012)	(869)
Net Exposure	0	$ 0
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	$ 1,000