Significant Accounting Policies - Recently Adopted Accounting Standards - Statement of Operations (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
Accounting Changes
Net sales	$ 98,972	$ 126,757	$ 157,779	$ 158,574	$ 139,661	$ 129,308	$ 112,218	$ 94,499	$ 542,082	$ 475,686	$ 331,702
Cost of sales									348,363	299,458	198,604
Income tax expense (benefit)									(26,746)	(37,594)	2,823
Net income (loss)	$ (144,674)	$ (8,953)	$ (237,634)	$ (15,827)	$ (8,479)	$ (23,740)	$ (20,817)	$ 1,640	$ (407,088)	$ (51,396)	$ (122,027)
Diluted earnings (loss) per share (in dollars per share)	$ (3.11)	$ (0.19)	$ (5.02)	$ (0.34)	$ (0.18)	$ (0.51)	$ (0.49)	$ 0.04	$ (8.63)	$ (1.16)	$ (3.10)
Previously Reported | ASU 2014-09, Revenue from Contracts with Customers
Accounting Changes
Net sales										$ 484,756	$ 332,451
Cost of sales										300,438	199,593
Income tax expense (benefit)										(36,107)	2,766
Net income (loss)										$ (44,793)	$ (122,210)
Diluted earnings (loss) per share (in dollars per share)										$ (1.01)	$ (3.11)
Adjustments for adoption of guidance | ASU 2014-09, Revenue from Contracts with Customers
Accounting Changes
Net sales										$ (9,070)	$ (749)
Cost of sales										(980)	(989)
Income tax expense (benefit)										(1,487)	57
Net income (loss)										$ (6,603)	$ 183
Diluted earnings (loss) per share (in dollars per share)										$ (0.15)	$ 0.01