Offsetting Arrangements - Liabilities With Enforceable Netting Arrangements (Details) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Offsetting [Abstract]
Derivative, Net Amount of Liabilities Presented in Statement of Condition	$ 4,116	$ 6,308
Derivative, Counterparty Netting	0	0
Derivative, Collateral Provided	(58)	(19)
Derivative, Net Amount	4,058	6,289
Repurchase Agreements and Securities Lending, Net Amount of Liabilities Presented in Statement of Condition	11,297	15,405
Repurchase Agreements and Securities Lending, Counterparty Netting	(48)	(128)
Repurchase Agreements and Securities Lending, Collateral Provided	(9,053)	(13,872)
Repurchase Agreements and Securities Lending, Net Amount	2,196	1,405
Total, Net Amount of Liabilities Presented in Statement of Condition	15,413	21,713
Total, Counterparty Netting	(48)	(128)
Total, Collateral Provided	(9,111)	(13,891)
Total, Net Amount	$ 6,254	$ 7,694