Stockholders' Equity - Changes in Stockholder's Equity (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended		12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)			30,801,255				30,801,255
Beginning balance	$ 87,861	$ 96,926	$ 128,688	$ 128,885	$ 120,065	$ 109,596	$ 128,688	$ 109,596
Share-based compensation expense	742	854	862	721	719	761	2,458
Total comprehensive loss	$ 6,742	(9,919)	(32,624)	1,182	8,101	9,780	$ (35,801)	19,063
Ending balance (in shares)	30,985,669						30,985,669
Ending balance	$ 95,345	$ 87,861	$ 96,926	$ 130,788	$ 128,885	120,065	$ 95,345	130,788	$ 109,596
Accounting Standards Update [Extensible List]									us-gaap:AccountingStandardsUpdate201602Member
Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance						$ (72)		$ (72)
Ending balance									$ (72)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance (in shares)	30,985,669	30,847,269	30,801,255	30,581,274	30,512,843	30,512,843	30,801,255	30,512,843
Beginning balance	$ 309	$ 323	$ 323	$ 319	$ 318	$ 318	$ 323	$ 318
Share-based compensation expense (in shares)		138,400	46,014		68,431		184,414
Share-based compensation expense	$ 1	$ (14)			$ 1		$ (13)
Ending balance (in shares)	30,985,669	30,985,669	30,847,269	30,581,274	30,581,274	30,512,843	30,985,669	30,581,274	30,512,843
Ending balance	$ 310	$ 309	$ 323	$ 319	$ 319	$ 318	$ 310	$ 319	$ 318
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(11,230)	(11,230)	(11,230)	(10,245)	(10,245)	(10,245)	(11,230)	(10,245)
Ending balance	(11,230)	(11,230)	(11,230)	(10,245)	(10,245)	(10,245)	(11,230)	(10,245)	(10,245)
Additional Paid In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	247,582	246,714	245,852	244,486	243,768	243,007	245,852	243,007
Share-based compensation expense	741	868	862	721	718	761	2,471
Ending balance	248,323	247,582	246,714	245,207	244,486	243,768	248,323	245,207	243,007
Retained Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(97,398)	(84,901)	(60,307)	(59,953)	(66,099)	(76,013)	(60,307)	(76,013)
Total comprehensive loss	4,178	(12,497)	(24,594)	7,180	6,146	9,986	(32,913)
Ending balance	(93,220)	(97,398)	(84,901)	(52,773)	(59,953)	(66,099)	(93,220)	(52,773)	(76,013)
Retained Deficit | Cumulative Effect, Period of Adoption, Adjustment
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance						(72)		(72)
Ending balance									(72)
Accumulated  Other Comp. Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(51,402)	(53,980)	(45,950)	(45,722)	(47,677)	(47,471)	(45,950)	(47,471)
Total comprehensive loss	2,564	2,578	(8,030)	(5,998)	1,955	(206)	(2,888)
Ending balance	$ (48,838)	$ (51,402)	$ (53,980)	$ (51,720)	$ (45,722)	$ (47,677)	$ (48,838)	$ (51,720)	$ (47,471)