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	$ 127	$ 166	$ 305	$ 334
Other comprehensive income (loss):
Fair market value adjustment on cash flow hedges, net of income tax provision of $1 million				2
Reclassification adjustment for net realized losses on cash flow hedges included in interest expense, net of income tax provision of $3 million, $1 million, $4 million and $2 million	5	2	7	4
Foreign currency translation		3	(10)	5
Total other comprehensive income (loss)	5	5	(3)	11
Comprehensive income	$ 132	$ 171	$ 302	$ 345