Netting Arrangements Narratives (Details) - USD ($)	Jun. 30, 2016	Dec. 31, 2015
Derivative [Line Items]
Fair value of non-cash collateral we pledged	$ 1,200,000,000	$ 197,000,000
Fair value of non-cash collateral received	41,500,000,000	38,000,000,000
Fair value of non-cash collateral received that can be resold or repledged	38,900,000,000	36,200,000,000
Fair value of securities received as collateral that have been resold or repledge	0	0
Derivative assets not subject to enforceable master netting arrangement	27,000,000	28,000,000
Derivative liabilities not subject to enforceable master netting arrangement	1,000,000	2,000,000
Cash and Cash Equivalents [Member]
Derivative [Line Items]
Securities purchased under agreements to resell or similar arrangements	$ 19,100,000,000	$ 10,600,000,000