Supplemental Condensed Consolidating Financial Information - Condensed Consolidating Statements of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Condensed Statement of Income Captions [Line Items]
Net income	$ 42	$ 46	$ 99	$ 113
Other comprehensive income (loss), net of tax	(1)	2	7	1
Comprehensive income	41	48	106	114
Eliminations
Condensed Statement of Income Captions [Line Items]
Net income	(65)	(64)	(144)	(155)
Other comprehensive income (loss), net of tax	1	(1)	(6)	0
Comprehensive income	(64)	(65)	(150)	(155)
Parent Guarantor | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net income	42	46	99	113
Other comprehensive income (loss), net of tax	(1)	2	7	1
Comprehensive income	41	48	106	114
Other Guarantors | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net income	5	4	8	17
Other comprehensive income (loss), net of tax	0	0	0	0
Comprehensive income	5	4	8	17
Non-Guarantors | Reportable Legal Entities
Condensed Statement of Income Captions [Line Items]
Net income	60	60	136	138
Other comprehensive income (loss), net of tax	(1)	1	6	0
Comprehensive income	$ 59	$ 61	$ 142	$ 138