Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Revenue	$ 495,781	$ 478,674	$ 989,667	$ 895,087
Cost of services and products	453,798	448,946	920,097	846,531
Gross margin	41,983	29,728	69,570	48,556
Selling, general and administrative expense	51,618	49,365	100,919	95,342
Income (loss) from operations	(9,635)	(19,637)	(31,349)	(46,786)
Interest income	1,848	2,950	4,452	5,542
Interest expense, net of amounts capitalized	(10,199)	(8,802)	(19,623)	(18,173)
Equity in income (losses) of unconsolidated affiliates	0	(737)	(164)	(1,580)
Other income (expense), net	7	(3,556)	726	(12,030)
Income (loss) before income taxes	(17,979)	(29,782)	(45,958)	(73,027)
Provision (benefit) for income taxes	17,203	3,294	14,051	9,182
Net Income (Loss)	$ (35,182)	$ (33,076)	$ (60,009)	$ (82,209)
Weighted-average shares outstanding
Basic (in shares)	98,929	98,531	98,822	98,457
Diluted (in shares)	98,929	98,531	98,822	98,457
Earnings (loss) per share
Basic (in dollars per share)	$ (0.36)	$ (0.34)	$ (0.61)	$ (0.83)
Diluted (in dollars per share)	$ (0.36)	$ (0.34)	$ (0.61)	$ (0.83)