CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income		$ 270	$ 270	$ 445	$ 453
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	[1]	22	(21)	42	(46)
Fixed price diesel swaps		0	1	1	1
Other comprehensive income (loss)		22	(20)	43	(45)
Comprehensive income (loss)	[1]	$ 292	$ 250	$ 488	$ 408

[1] There were no material reclassifications from accumulated other comprehensive loss reflected in other comprehensive income (loss) during 2019 or 2018. There is no tax impact related to the foreign currency translation adjustments, as the earnings are considered permanently reinvested. We have historically considered the undistributed earnings of our foreign subsidiaries to be indefinitely reinvested. We have not repatriated funds to the U.S. to satisfy domestic liquidity needs, nor do we anticipate the need to do so. If we determine that all or a portion of our foreign earnings are no longer indefinitely reinvested, we may be subject to additional foreign withholding taxes and U.S. state income taxes. There were no material taxes associated with other comprehensive income (loss) during 2019 or 2018.