Results of Reportable Segment (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Operating revenues		$ 421	$ 422	$ 1,242	$ 1,213
Depreciation and amortization expense		52	50	155	148
Impairment charges		0	0	19	24
Operating income (loss)		60	74	51	66
North America [Member]
Segment Reporting Information [Line Items]
Operating revenues		421	411	1,235	1,184
Depreciation and amortization expense		52	52	155	147
Impairment charges		0	0	19	24
Operating income (loss)		62	71	55	66
All Other [Member]
Segment Reporting Information [Line Items]
Operating revenues	[1]	0	11	7	29
Depreciation and amortization expense	[1]	0	(2)	0	1
Impairment charges	[1]	0	0	0	0
Operating income (loss)	[1]	$ (2)	$ 3	$ (4)	$ 0

[1] (1)All other is comprised of the financial results of our operations outside of North America.