Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Statement of Comprehensive Income [Abstract]
Net Income	$ 53	$ 53	$ 106	$ 128
Other Comprehensive Income
Losses on treasury rate locks reclassified into income	0	0	0	0
Pension and other postretirement benefit plans	3	(3)	5	(2)
Other comprehensive income (loss), before income taxes	3	(3)	5	(2)
Income tax expense (benefit) related to other comprehensive income		(1)	1	(1)
Other comprehensive income (loss), net of income taxes	3	(2)	4	(1)
Comprehensive Income	$ 56	$ 51	$ 110	$ 127