Derivatives Instruments - Collateral (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Derivative
Derivatives Assets, Subject to Master Netting Arrangement	$ 56,615	$ 45,982
Derivative, Collateral, Obligation to Return Securities and/or Cash Held by Third-Party Custodians	(9,833)	(11,350)
Derivative Assets, Net Exposure After Liquid Securities Collateral, Assets Subject to a Master Netting Arrangement	46,782	34,632
Derivatives Liabilities, Subject to Master Netting Arrangement	52,123	49,290
Derivative, Collateral, Right to Reclaim Securities and/or Cash Held at Third-Party Custodians	(8,740)	(20,109)
Derivative Liabilities, Net Amount After Liquid Securities and/or Cash Collateral Held at Third-Party Custodians, Liabilities Subject to a Master Netting Agreement	$ 43,383	$ 29,181