Condensed Consolidated Statement of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]
Beginning balance at Dec. 31, 2017	$ 212,705	$ 196	$ (26,096)	$ 226,006	$ (716)	$ 13,315
Beginning balance, shares at Dec. 31, 2017		19,586,000	805,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	10,168				10,168
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification	8,954
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | Accounting Standards Update 2014-09 [Member]					15,043
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification | Accounting Standards Update 2016-01 [Member]						(6,089)
Other comprehensive income, net of tax	1,590					1,590
Common and treasury stock transactions:
Stock-based compensation	1,776			1,776
Vesting of equity, net of tax withholdings	(2,233)		$ (4,614)	(6,847)
Dividends, Cash	(2,460)				(2,460)
Vesting of equity, net of tax withholdings, shares			138,000
Dividend equivalents on restricted stock units	11				11
Ending balance at Mar. 31, 2018	230,489	$ 196	$ (21,482)	220,935	22,024	8,816
Ending balance, shares at Mar. 31, 2018		19,586,000	667,000
Beginning balance at Dec. 31, 2017	212,705	$ 196	$ (26,096)	226,006	(716)	13,315
Beginning balance, shares at Dec. 31, 2017		19,586,000	805,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	38,100
Other comprehensive income, net of tax	(3,107)
Ending balance at Sep. 30, 2018	253,833	$ 196	$ (20,298)	224,962	44,854	4,119
Ending balance, shares at Sep. 30, 2018		19,586,000	632,000
Beginning balance at Mar. 31, 2018	230,489	$ 196	$ (21,482)	220,935	22,024	8,816
Beginning balance, shares at Mar. 31, 2018		19,586,000	667,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	11,463				11,463
Other comprehensive income, net of tax	(3,816)					(3,816)
Common and treasury stock transactions:
Stock-based compensation	2,076			2,076
Vesting of equity, net of tax withholdings	0		$ (989)	(989)
Dividends, Cash	(2,465)				(2,465)
Vesting of equity, net of tax withholdings, shares			29,000
Re-issuance of treasury stock	(224)		$ (195)	(29)
Re-issuance of treasury stock, shares			(6,000)
Dividend equivalents on restricted stock units	106				106
Ending balance at Jun. 30, 2018	237,865	$ 196	$ (20,298)	222,051	30,916	5,000
Ending balance, shares at Jun. 30, 2018		19,586,000	632,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16,469				16,469
Other comprehensive income, net of tax	(881)					(881)
Common and treasury stock transactions:
Stock-based compensation	2,911			2,911
Dividends, Cash	(2,464)				2,464
Dividend equivalents on restricted stock units	67				67
Ending balance at Sep. 30, 2018	253,833	$ 196	$ (20,298)	224,962	44,854	4,119
Ending balance, shares at Sep. 30, 2018		19,586,000	632,000
Beginning balance at Dec. 31, 2018	$ 267,156	$ 196	$ (20,298)	227,147	56,049	4,062
Beginning balance, shares at Dec. 31, 2018	18,954,275	19,586,000	632,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 12,087				12,087
Other comprehensive income, net of tax	320					320
Common and treasury stock transactions:
Stock-based compensation	1,343			1,343
Vesting of equity, net of tax withholdings	4,552		$ (5,155)	9,707
Dividends, Cash	(2,848)				(2,848)
Vesting of equity, net of tax withholdings, shares			160,000
Dividend equivalents on restricted stock units	87				87
Ending balance at Mar. 31, 2019	273,419	$ 196	$ (15,143)	218,783	65,201	4,382
Ending balance, shares at Mar. 31, 2019		19,586,000	472,000
Beginning balance at Dec. 31, 2018	$ 267,156	$ 196	$ (20,298)	227,147	56,049	4,062
Beginning balance, shares at Dec. 31, 2018	18,954,275	19,586,000	632,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 36,314
Other comprehensive income, net of tax	(1,012)					(1,012)
Ending balance at Sep. 30, 2019	$ 296,635	$ 196	$ (14,795)	224,687	83,497	3,050
Ending balance, shares at Sep. 30, 2019	19,127,401	19,586,000	458,000
Beginning balance at Mar. 31, 2019	$ 273,419	$ 196	$ (15,143)	218,783	65,201	4,382
Beginning balance, shares at Mar. 31, 2019		19,586,000	472,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	14,280				14,280
Other comprehensive income, net of tax	5					5
Common and treasury stock transactions:
Stock-based compensation	3,368			3,368
Vesting of equity, net of tax withholdings	0		$ 0	0
Dividends, Cash	(2,867)				(2,867)
Vesting of equity, net of tax withholdings, shares			3,000
Re-issuance of treasury stock	(345)		$ (348)	3
Re-issuance of treasury stock, shares			11,000
Dividend equivalents on restricted stock units	101				101
Ending balance at Jun. 30, 2019	288,449	$ 196	$ (14,795)	222,148	76,513	4,387
Ending balance, shares at Jun. 30, 2019		19,586,000	458,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,947				9,947
Other comprehensive income, net of tax	(1,337)					(1,337)
Common and treasury stock transactions:
Stock-based compensation	2,539			2,539
Dividends, Cash	(2,870)				2,870
Dividend equivalents on restricted stock units	93				93
Ending balance at Sep. 30, 2019	$ 296,635	$ 196	$ (14,795)	$ 224,687	$ 83,497	$ 3,050
Ending balance, shares at Sep. 30, 2019	19,127,401	19,586,000	458,000