Business Segment and Related Information - Reconciliation Of Segment Gross Profit to Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment gross (loss) profit	$ (2,065)	$ 30,549	$ 13,314	$ 49,647
General and administrative expenses	17,400	18,937	31,385	33,319
Interest expense, net	4,102	5,543	9,154	9,674
Income from equity method investment	663	699	1,217	1,286
Income tax provision	(5,628)	2,906	(6,389)	2,906
Net (loss) income	(17,276)	3,862	(19,619)	5,034
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Segment gross (loss) profit	(2,065)	30,549	13,314	49,647
Segment Reconciling Items
Segment Reporting, Revenue Reconciling Item [Line Items]
General and administrative expenses	(17,400)	(18,937)	(31,385)	(33,319)
Interest expense, net	(4,102)	(5,543)	(9,154)	(9,674)
Income from equity method investment	663	699	1,217	1,286
Income tax provision	$ 5,628	$ (2,906)	$ 6,389	$ (2,906)