Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 214	$ 218	$ 715	$ 523
Other comprehensive income (loss):
Fair market value adjustment on cash flow hedges, net of income tax benefit of $1 million	0	(1)	0	(1)
Reclassification adjustment for net realized losses on cash flow hedges included in interest expense, net of income tax provision of $1 million, $1 million, $3 million and $6 million	2	2	5	9
Foreign currency translation	3	(10)	0	(20)
Total other comprehensive income (loss)	5	(9)	5	(12)
Comprehensive income	$ 219	$ 209	$ 720	$ 511