Offsetting Arrangements - Assets With Enforceable Netting Arrangements (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Offsetting [Abstract]
Derivative, Net Amount of Assets Presented in Statement of Condition	$ 8,048	$ 7,934
Derivatives, Counterparty Netting	0	0
Derivatives, Collateral Received	(1,442)	(1,490)
Derivatives, Net Amount	6,606	6,444
Resale Agreements and Securities Borrowing, Resale Agreements and Securities Borrowing, Net Amount of Assets Presented in Statement of Condition	31,180	18,331
Resale Agreements and Securities Borrowing, Counterparty Netting	(283)	(128)
Resale Agreements and Securities Borrowing, Collateral Received	(30,842)	(18,157)
Resale Agreements and Securities Borrowing, Net Amount	55	46
Total, Net Amounts of Assets Presented in Statement of Condition	39,228	26,265
Total, Counterparty Netting	(283)	(128)
Total, Collateral Received	(32,284)	(19,647)
Total, Net Amount	$ 6,661	$ 6,490