Stockholders' Equity - Changes in Stockholder's Equity (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Jan. 01, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 136,502	$ 126,651	$ 115,038	$ 94,541	$ 86,400	$ 74,742	$ 115,038
Beginning balance (in shares)			30,512,843				30,512,843
Share-based compensation expense	721	719	$ 761	780	844	673	$ 2,201
Total comprehensive income	$ 2,522	9,132	10,924	9,994	7,297	10,985	$ 22,578
Ending balance (in shares)	30,581,274						30,581,274
Ending balance	$ 139,745	136,502	126,651	105,315	94,541	86,400	$ 139,745
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	$ 319	$ 318	$ 318	$ 304	$ 304	$ 304	$ 318
Beginning balance (in shares)	30,581,000	30,513,000	30,513,000	30,219,000	30,219,000	30,219,000	30,513,000
Share-based compensation expense (in shares)		68,000					68,000
Share-based compensation expense		$ 1					$ 1
Ending balance (in shares)	30,581,000	30,581,000	30,513,000	30,219,000	30,219,000	30,219,000	30,581,000
Ending balance	$ 319	$ 319	$ 318	$ 304	$ 304	$ 304	$ 319
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(10,245)	(10,245)	(10,245)	(9,114)	(9,114)	(9,114)	(10,245)
Ending balance	(10,245)	(10,245)	(10,245)	(9,114)	(9,114)	(9,114)	(10,245)
Additional Paid In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	244,486	243,768	243,007	241,387	240,543	239,870	243,007
Share-based compensation expense	721	718	761	780	844	673	2,200
Ending balance	245,207	244,486	243,768	242,167	241,387	240,543	245,207
Retained Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(52,336)	(59,513)	(70,571)	(92,035)	(105,230)	(115,083)	(70,571)
Share-based compensation expense						0
Total comprehensive income	8,520	7,177	11,130	12,583	13,195	9,853	26,827
Ending balance	(43,816)	(52,336)	(59,513)	(79,452)	(92,035)	(105,230)	(43,816)
Accumulated Other Comp. Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(45,722)	(47,677)	(47,471)	(46,001)	(40,103)	(41,235)	(47,471)
Total comprehensive income	(5,998)	1,955	(206)	(2,589)	(5,898)	1,132	(4,249)
Ending balance	$ (51,720)	$ (45,722)	$ (47,677)	$ (48,590)	$ (46,001)	$ (40,103)	$ (51,720)
Adoption of ASU 842
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adoption of Topic 842								$ (72)
Adoption of ASU 842 | Retained Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adoption of Topic 842								$ (72)