Consolidated Statements Of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net income	$ 285	$ 257	$ 32
Other Comprehensive Income (Loss) from Continuing Operations
Losses arising during period			(100)
Amount of losses reclassified into income	39	81	135
Net gains on commodity derivatives	39	81	35
Losses on treasury rate locks reclassified into income		1	18
Pension and other postretirement benefit plans	(14)	(11)
Other comprehensive income, before income taxes	25	71	53
Income tax expense related to other comprehensive income	10	28	21
Other comprehensive income from continuing operations, net of income taxes	15	43	32
Other Comprehensive Income from Discontinued Operations, Net of Income Taxes			103
Comprehensive Income	$ 300	$ 300	$ 167