Income Taxes Components of Net Deferred Income Tax Liability (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred income tax assets:
Regulatory liabilities	$ 355	$ 346
Employee benefits	98	219
Derivative contracts and unamortized contract values	76	109
State carryforwards	68	69
Loss contingencies	67	61
Asset retirement obligations	48	46
Other	86	106
Total deferred income tax assets	798	956
Deferred income tax liabilities:
Property, plant and equipment	(4,528)	(4,269)
Regulatory assets	(525)	(695)
Other	(38)	(48)
Total deferred income tax liabilities	(5,091)	(5,012)
Net deferred income tax liability	(4,293)	(4,056)
Reflected as:
Deferred income taxes - current assets	66	112
Deferred income taxes - noncurrent liabilities	$ (4,359)	$ (4,168)