Fair Values Of Assets And Liabilities Level 3 Rollforward (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 7			$ 2
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings	2		4
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases			7
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	(3)		(5)	(2)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	8		8
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	(20)			(6)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings	1		(4)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases			(19)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	7		10	6
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	$ (16)		$ (16)