Selected Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Selected Quarterly Financial Information [Abstract]
Revenues	$ 99,211	$ 125,073	$ 159,767	$ 136,843	$ 162,214	$ 140,162	$ 137,420	$ 138,757	$ 520,894	$ 578,553	$ 578,236
Gross profit	(20,880)	5,938	20,769	15,822	27,751	10,757	15,397	12,985	21,649	66,890	67,482
Operating (loss) income	(104,795)	(7,405)	4,591	7,069	10,840	(5,354)	(2,466)	(1,482)	(100,540)	1,538	4,074
(Loss) income before income taxes	(106,727)	(9,427)	3,909	5,590	9,306	(6,703)	(3,917)	(2,827)	(106,655)	(4,141)	$ (2,039)
Net (loss) income	$ (94,416)	$ (6,356)	$ 2,249	$ 4,101	$ 9,538	$ (5,037)	$ (2,293)	$ (1,808)	$ (94,422)	$ 400
Earnings Per Share, Basic and Diluted [Abstract]
Basic (USD per share)	$ (3.32)	$ (0.22)	$ 0.08	$ 0.15	$ 0.34	$ (0.18)	$ (0.08)	$ (0.07)	$ (3.31)	$ 0.01	$ (0.13)
Diluted income (loss) per share (USD per share)	$ (3.32)	$ (0.22)	$ 0.08	$ 0.14	$ 0.34	$ (0.18)	$ (0.08)	$ (0.07)	$ (3.31)	$ 0.01	$ (0.13)