Offsetting Assets and Liabilities (Assets Subject to Netting) (Details) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014
Derivatives [Abstract]
Gross amounts of recognized assets		$ 4,093	$ 4,101
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(2,882)	(3,224)
Cash collateral		(608)	(362)
Securities collateral		(445)	(418)
Net amount		158	97
Securities borrowed [Abstract]
Gross amounts of recognized assets		274	215
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(38)	(49)
Securities borrowed		(227)	(163)
Net amount		9	3
Total [Abstract]
Gross amounts of recognized assets		4,367	4,316
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(2,920)	(3,273)
Cash collateral		(608)	(362)
Securities collateral		(672)	(581)
Net amount		167	100
OTC [Member]
Derivatives [Abstract]
Gross amounts of recognized assets		3,473	3,735
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(2,460)	(3,000)
Cash collateral		(519)	(281)
Securities collateral		(445)	(418)
Net amount		49	36
OTC cleared [Member]
Derivatives [Abstract]
Gross amounts of recognized assets		507	305
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(417)	(224)
Cash collateral		(89)	(81)
Net amount		1
Exchange-traded [Member]
Derivatives [Abstract]
Gross amounts of recognized assets		113	61
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(5)
Net amount		$ 108	$ 61

[1] Represents the amount of assets that could be offset by liabilities with the same counterparty under master netting or similar arrangements that management elects not to offset on the Consolidated Balance Sheets.