Derivative Instruments (Details 4) (Not Designated as Hedging Instrument, Subject to Regulatory Accounting, Excluded from Earnings, USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Unrealized Gain (Loss) on Derivative Instrument	$ (44)	$ (344)
Realized Gain (Loss) on Derivative Instrument	240	247
NUGs
Derivative [Line Items]
Unrealized Gain (Loss) on Derivative Instrument	(23)	(201)
Realized Gain (Loss) on Derivative Instrument	75	240
LCAPP
Derivative [Line Items]
Unrealized Gain (Loss) on Derivative Instrument	(22)	(144)
Realized Gain (Loss) on Derivative Instrument	166	0
Regulated FTRs
Derivative [Line Items]
Unrealized Gain (Loss) on Derivative Instrument	1	1
Realized Gain (Loss) on Derivative Instrument	$ (1)	$ 7