Basis of Presentation - Change in Accounting Policy - Statement of Operations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accounting Changes
Net sales	$ 126,757	$ 129,308	$ 443,110	$ 336,025
Cost of sales	80,372	78,779	284,651	215,150
Income tax expense (benefit)	301	(2,466)	(27,954)	(26,334)
Net income (loss)	$ (8,953)	$ (23,740)	$ (262,414)	$ (42,918)
Diluted earnings (loss) per share (in dollars per share)	$ (0.19)	$ (0.51)	$ (5.55)	$ (1.00)
Previously Reported | Accounting Standards Update 2014-09, Revenue from Contracts with Customers
Accounting Changes
Net sales		$ 131,872		$ 341,324
Cost of sales		78,811		215,344
Income tax expense (benefit)		(1,790)		(24,969)
Net income (loss)		$ (21,884)		$ (39,177)
Diluted earnings (loss) per share (in dollars per share)		$ (0.47)		$ (0.91)
Adjustments for adoption of guidance | Accounting Standards Update 2014-09, Revenue from Contracts with Customers
Accounting Changes
Net sales		$ (2,564)		$ (5,299)
Cost of sales		(32)		(194)
Income tax expense (benefit)		(676)		(1,365)
Net income (loss)		$ (1,856)		$ (3,741)
Diluted earnings (loss) per share (in dollars per share)		$ (0.04)		$ (0.09)