Netting Arrangements (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
Securities Received as Collateral [Abstract]
Securities sold under agreements to repurchase	$ 0	$ 0
Securities Purchased under Agreements to Resell or Similar Arrangements [Member]
Securities Received as Collateral [Abstract]
Fair value of non-cash collateral accepted	58,100,000,000	46,200,000,000
Fair value of non-cash collateral accepted that can be resold or repledged	44,800,000,000	25,000,000,000
Fair value of securities accepted as collateral that have been resold or repledged	0	0
OTC risk management derivatives [Member]
Securities Received as Collateral [Abstract]
Fair value of non-cash collateral accepted	$ 23,000,000	$ 54,000,000