Derivative Financial Instruments (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Asset derivatives
Asset derivatives gross amount	$ 215	$ 169
Derivative assets net amount on balance sheet	202	147
Liability derivatives
Liability derivatives gross amount	(692)	(664)
Derivative liabilities net amount on balance sheet	(680)	(645)
OTC derivatives
Asset derivatives
Asset derivatives gross amount	20	52
Offsets of derivative assets under counterparty netting	(13)	(29)
Derivative asset offsets under cash collateral received	(3)	(18)
Derivative assets net amount on balance sheet	4	5
Derivative assets pledged under securities collateral	(2)	(5)
Derivative assets net amount	2
Liability derivatives
Liability derivatives gross amount	(35)	(63)
Offsets of derivative liabilities under counterparty netting	13	29
Derivative liability offsets under cash collateral pledged	(2)
Derivative liabilities net amount on balance sheet	(24)	(34)
Derivative liabilities received under securities collateral	23	25
Derivative liabilities net amount	$ (1)	$ (9)