Fair Value of FInancial Instruments Fair Value Unobservable Input Reconciliation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Net realized and unrealized losses	$ 134	$ 15
Purchases	0	1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issues	0	(1)
Settlements	(1)	0
Net transfers out of Level 3 to Level 2	(10)	(76)
Net liabilities from price risk management activities as of end of year	139	16	79
Level 3 net unrealized losses that have been fully offset by the effect of regulatory accounting	133	14
Net realized losses	$ 1	$ 1