Stockholders' Equity Stockholders' Equity - Changes In Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended								6 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)				30,512,843					30,512,843		30,512,843		30,512,843
Beginning balance	$ 130,788	$ 128,885	$ 120,065	$ 109,596	$ 100,657	$ 91,189	$ 83,572	$ 72,323	$ 109,596	$ 72,323	$ 109,596	$ 72,323	$ 109,596	$ 72,323	$ 65,835
Issuance of restricted stock	4				14
Surrender of common stock by employees	(985)				(1,131)
Share-based compensation expense	645	721	719	761	840	780	844	673
Total comprehensive income	$ (1,764)	1,182	8,101	9,780	$ 9,216	8,688	6,773	10,576	17,881	17,349	19,063	26,037	$ 17,299	$ 35,253	5,341
Ending balance (in shares)	30,801,255				30,512,843								30,801,255	30,512,843
Ending balance	$ 128,688	$ 130,788	$ 128,885	$ 120,065	$ 109,596	$ 100,657	$ 91,189	$ 83,572	$ 128,885	$ 91,189	$ 130,788	$ 100,657	$ 128,688	$ 109,596	$ 72,323
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance (in shares)	30,581,000	30,581,000	30,513,000	30,512,843	30,219,000	30,219,000	30,219,000	30,219,278	30,512,843	30,219,278	30,512,843	30,219,278	30,512,843	30,219,278	29,871,354
Beginning balance	$ 319	$ 319	$ 318	$ 318	$ 304	$ 304	$ 304	$ 304	$ 318	$ 304	$ 318	$ 304	$ 318	$ 304	$ 299
Issuance of restricted stock (in shares)	351,000				452,000								418,553	452,021	509,306
Issuance of restricted stock	$ 4				$ 14								$ 5	$ 14	$ 5
Surrender of common stock by employees (in shares)	(131,000)				(158,000)								(130,141)	(158,456)	(161,382)
Share-based compensation expense (in shares)			68,000
Share-based compensation expense			$ 1
Ending balance (in shares)	30,801,255	30,581,000	30,581,000	30,513,000	30,512,843	30,219,000	30,219,000	30,219,000	30,581,000	30,219,000	30,581,000	30,219,000	30,801,255	30,512,843	30,219,278
Ending balance	$ 323	$ 319	$ 319	$ 318	$ 318	$ 304	$ 304	$ 304	$ 319	$ 304	$ 319	$ 304	$ 323	$ 318	$ 304
Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(10,245)	(10,245)	(10,245)	(10,245)	(9,114)	(9,114)	(9,114)	(9,114)	(10,245)	(9,114)	(10,245)	(9,114)	(10,245)	(9,114)	(7,753)
Surrender of common stock by employees	(985)				(1,131)								(985)	(1,131)	(1,361)
Ending balance	(11,230)	(10,245)	(10,245)	(10,245)	(10,245)	(9,114)	(9,114)	(9,114)	(10,245)	(9,114)	(10,245)	(9,114)	(11,230)	(10,245)	(9,114)
Additional Paid In Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	245,207	244,486	243,768	243,007	242,167	241,387	240,543	239,870	243,007	239,870	243,007	239,870	243,007	239,870	237,367
Share-based compensation expense	645	721	718	761	840	780	844	673
Ending balance	245,852	245,207	244,486	243,768	243,007	242,167	241,387	240,543	244,486	241,387	245,207	242,167	245,852	243,007	239,870
Retained Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(52,773)	(59,953)	(66,099)	(76,013)	(84,110)	(95,387)	(108,058)	(117,502)	(76,013)	(117,502)	(76,013)	(117,502)	(76,013)	(117,502)	(115,233)
Cumulative effect of adoption of Topic 842																$ (72)
Total comprehensive income	(7,534)	7,180	6,146	9,986	8,097	11,277	12,671						15,778	41,489	(2,269)
Ending balance	(60,307)	(52,773)	(59,953)	(66,099)	(76,013)	(84,110)	(95,387)	(108,058)	(59,953)	(95,387)	(52,773)	(84,110)	(60,307)	(76,013)	(117,502)
Accum. Other Comp. Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(51,720)	(45,722)	(47,677)	(47,471)	(48,590)	(46,001)	(40,103)	(41,235)	(47,471)	(41,235)	(47,471)	(41,235)	(47,471)	(41,235)	(48,845)
Total comprehensive income	5,770	(5,998)	1,955	(206)	1,119	(2,589)	(5,898)	1,132						(6,236)	7,610
Ending balance	$ (45,950)	$ (51,720)	$ (45,722)	$ (47,677)	$ (47,471)	$ (48,590)	$ (46,001)	(40,103)	$ (45,722)	$ (46,001)	$ (51,720)	$ (48,590)	$ (45,950)	$ (47,471)	$ (41,235)
Adoption of ASU 842
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adoption of Topic 842																(72)
Total comprehensive income								10,576
Adoption of ASU 842 | Retained Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adoption of Topic 842																$ (72)
Total comprehensive income								$ 9,444