Offsetting Assets and Liabilities (Assets Subject to Netting) (Details) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Derivatives [Abstract]
Gross amounts of recognized assets		$ 3,797	$ 4,101
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(3,035)	(3,224)
Cash collateral		(378)	(362)
Securities collateral		(215)	(418)
Net amount		169	97
Securities borrowed [Abstract]
Gross amounts of recognized assets		284	215
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(54)	(49)
Securities borrowed		(227)	(163)
Net amount		3	3
Total [Abstract]
Gross amounts of recognized assets		4,081	4,316
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(3,089)	(3,273)
Cash collateral		(378)	(362)
Securities collateral		(442)	(581)
Net amount		172	100
OTC [Member]
Derivatives [Abstract]
Gross amounts of recognized assets		3,398	3,735
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(2,791)	(3,000)
Cash collateral		(299)	(281)
Securities collateral		(215)	(418)
Net amount		93	36
OTC cleared [Member]
Derivatives [Abstract]
Gross amounts of recognized assets		323	305
Gross amounts not offset in the consolidated balance sheets [Abstract]
Financial instruments	[1]	(244)	(224)
Cash collateral		(79)	(81)
Exchange-traded [Member]
Derivatives [Abstract]
Gross amounts of recognized assets		76	61
Gross amounts not offset in the consolidated balance sheets [Abstract]
Net amount		$ 76	$ 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.