CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income		$ 169	$ 215	$ 86	$ 115	$ 194	$ 192	$ 94	$ 60	$ 585	$ 540	$ 387
Other comprehensive loss:
Foreign currency translation adjustments										(174)	(90)	(65)
Fixed price diesel swaps										(2)	(3)	0
Other comprehensive loss	[1]									(176)	(93)	(65)
Comprehensive income										$ 409	$ 447	$ 322

[1] There were no material reclassifications from accumulated other comprehensive (loss) income reflected in other comprehensive loss during the years ended December 31, 2015, 2014 or 2013. There is no tax impact related to the foreign currency translation adjustments, as the earnings are considered permanently reinvested. There were no material taxes associated with other comprehensive loss during the years ended December 31, 2015, 2014 or 2013.