Changes in Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Abstract]
AOCI, Translation adjustments, net of tax	$ (39)			$ (39)		$ (38)
AOCI, Post-retirement benefits, net of tax	(51)			(51)		(47)
Accumulated other comprehensive loss, net of tax	(90)			(90)		$ (85)
Other comprehensive income (loss), translation adjustments, before reclassification adjustment, net of tax				(1)
Other comprehensive income (loss), post-retirement benefits, before reclassification adjustment, net of tax				0
Other comprehensive income (loss), before reclassification adjustment, net of tax				(1)
Other comprehensive income, translation adjustments, gain (loss), reclassification from AOCI, net of tax				0
Other comprehensive income (loss), post-retirement benefits, gain (loss), reclassification adjustment from AOCI, after Tax				2
Other comprehensive income, gain (loss) reclassification adjustment from AOCI, net of tax				2
Other comprehensive loss, translation adjustments, net of tax	0	$ (108)		(1)	$ (75)
Other comprehensive income (loss), post-retirement benefits, net of tax	1	5		2	15
Other comprehensive loss, net of tax	$ 1	$ (103)	$ 43	1	$ (60)
Elimination of stranded tax effects resulting from tax legislation, translation adjustments and other				0
Elimination of stranded tax effects resulting from tax legislation, post-retirement benefits				(6)
Elimination of stranded tax effects resulting from tax legislation				$ (6)