CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income		$ 153	$ 187	$ 134	$ 92	$ 169	$ 215	$ 86	$ 115	$ 566	$ 585	$ 540
Other comprehensive income (loss):
Foreign currency translation adjustments										28	(174)	(90)
Fixed price diesel swaps										4	(2)	(3)
Other comprehensive income (loss)	[1]									32	(176)	(93)
Comprehensive income										$ 598	$ 409	$ 447

[1] There were no material reclassifications from accumulated other comprehensive loss reflected in other comprehensive income (loss) during the years ended December 31, 2016, 2015 or 2014. 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, 2016, 2015 or 2014.