Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenue	$ 497,647	$ 519,300	$ 1,487,314	$ 1,414,387
Cost of services and products	448,586	471,665	1,368,683	1,318,196
Gross margin	49,061	47,635	118,631	96,191
Selling, general and administrative expense	54,255	49,187	155,174	144,529
Income (loss) from operations	(5,194)	(1,552)	(36,543)	(48,338)
Interest income	2,089	2,645	6,541	8,187
Interest expense, net of amounts capitalized	(11,382)	(9,885)	(31,005)	(28,058)
Equity in income (losses) of unconsolidated affiliates	554	(1,684)	390	(3,264)
Other income (expense), net	(3,660)	5,632	(2,934)	(6,398)
Income (loss) before income taxes	(17,593)	(4,844)	(63,551)	(77,871)
Provision (benefit) for income taxes	7,930	$ 61,135	21,981	70,317
Net Income (Loss)	$ (25,523)		$ (85,532)	$ (148,188)
Weighted-average shares outstanding
Basic (in shares)	98,930	98,533	98,858	98,483
Diluted (in shares)	98,930	98,533	98,858	98,483
Earnings (loss) per share
Basic (in dollars per share)	$ (0.26)	$ (0.67)	$ (0.87)	$ (1.50)
Diluted (in dollars per share)	$ (0.26)	$ (0.67)	$ (0.87)	$ (1.50)