Derivative Financial Instruments (Details 2) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Asset derivatives
Asset derivatives gross amount	$ 232,000,000	$ 182,000,000
Derivative assets net amount on balance sheet	216,000,000	158,000,000
Liability derivatives
Liability derivatives gross amount	(697,000,000)	(669,000,000)
Derivative liabilities net amount on balance sheet	(685,000,000)	(646,000,000)
OTC derivatives
Asset derivatives
Asset derivatives gross amount	34,000,000	66,000,000
Offsets of derivative assets under counterparty netting	(16,000,000)	(35,000,000)
Derivative asset offsets under cash collateral received	(10,000,000)	(22,000,000)
Derivative assets net amount on balance sheet	8,000,000	9,000,000
Derivative assets pledged under securities collateral	(2,000,000)	(4,000,000)
Derivative assets net amount	6,000,000	5,000,000
Liability derivatives
Liability derivatives gross amount	(40,000,000)	(70,000,000)
Offsets of derivative liabilities under counterparty netting	16,000,000	35,000,000
Derivative liability offsets under cash collateral pledged	(2,000,000)	(2,000,000)
Derivative liabilities net amount on balance sheet	(26,000,000)	(37,000,000)
Derivative liabilities received under securities collateral	24,000,000	25,000,000
Derivative liabilities net amount	$ (2,000,000)	$ (12,000,000)