CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Earnings (Deficit)	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings (Deficit)	Total
BALANCE at Dec. 31, 2019			$ 411	$ (103,960)	$ 320,168	$ 368,685	$ 585,304
BALANCE (in shares) at Dec. 31, 2019			41,123,365
BALANCE (in shares) at Dec. 31, 2019				(4,465,448)
Increase (Decrease) in Stockholders' Equity
Net income						17,716	17,716
Issuance of Stock:
Issuance of restricted stock & performance stock				$ 1,054	801		1,855
Issuance of restricted stock & performance stock (in shares)				43,902
Shares received in lieu of tax withholding payment on vested restricted stock				$ (622)			(622)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)				(14,722)
Stock-based compensation					2,134		2,134
Dividends						(3,844)	(3,844)
Share repurchase				$ (8,985)			(8,985)
Share repurchase (in shares)				(237,359)
BALANCE at Mar. 31, 2020	$ (515)	$ (515)	$ 411	$ (112,513)	323,103	382,042	593,043
BALANCE (in shares) at Mar. 31, 2020			41,123,365
BALANCE (in shares) at Mar. 31, 2020				(4,673,627)
BALANCE at Dec. 31, 2019			$ 411	$ (103,960)	320,168	368,685	585,304
BALANCE (in shares) at Dec. 31, 2019			41,123,365
BALANCE (in shares) at Dec. 31, 2019				(4,465,448)
Increase (Decrease) in Stockholders' Equity
Net income							107,299
BALANCE at Sep. 30, 2020			$ 411	$ (118,551)	322,304	463,962	668,126
BALANCE (in shares) at Sep. 30, 2020			41,123,365
BALANCE (in shares) at Sep. 30, 2020				(4,723,672)
BALANCE at Mar. 31, 2020	$ (515)	$ (515)	$ 411	$ (112,513)	323,103	382,042	593,043
BALANCE (in shares) at Mar. 31, 2020			41,123,365
BALANCE (in shares) at Mar. 31, 2020				(4,673,627)
Increase (Decrease) in Stockholders' Equity
Net income						39,495	39,495
Issuance of Stock:
Issuance of shares for options exercised				$ 836	(280)		556
Issuance of shares for options exercised (in shares)				34,562
Issuance of restricted stock & performance stock				$ 2,048	(2,048)
Issuance of restricted stock & performance stock (in shares)				84,987
Shares received in lieu of tax withholding payment on vested restricted stock				$ (454)			(454)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)				(13,002)
Stock-based compensation					1,644		1,644
Dividends						(3,830)	(3,830)
Share repurchase				$ (2,021)			(2,021)
Share repurchase (in shares)				(52,991)
BALANCE at Jun. 30, 2020			$ 411	$ (112,104)	322,419	417,707	628,433
BALANCE (in shares) at Jun. 30, 2020			41,123,365
BALANCE (in shares) at Jun. 30, 2020				(4,620,071)
Increase (Decrease) in Stockholders' Equity
Net income						50,088	50,088
Issuance of Stock:
Issuance of shares for options exercised				$ 1,324	(325)		999
Issuance of shares for options exercised (in shares)				54,207
Stock-based compensation					210		210
Dividends						(3,833)	(3,833)
Share repurchase				$ (7,771)			(7,771)
Share repurchase (in shares)				(157,808)
BALANCE at Sep. 30, 2020			$ 411	$ (118,551)	322,304	463,962	668,126
BALANCE (in shares) at Sep. 30, 2020			41,123,365
BALANCE (in shares) at Sep. 30, 2020				(4,723,672)
BALANCE at Dec. 31, 2020			$ 411	$ (129,243)	322,451	502,810	$ 696,429
BALANCE (in shares) at Dec. 31, 2020			41,123,365				41,123,365
BALANCE (in shares) at Dec. 31, 2020				(4,935,186)			4,935,186
Increase (Decrease) in Stockholders' Equity
Net income						26,491	$ 26,491
Issuance of Stock:
Issuance of shares for options exercised				$ 1,616	(211)		1,405
Issuance of shares for options exercised (in shares)				61,454
Issuance of restricted stock & performance stock				$ 777	1,431		2,208
Issuance of restricted stock & performance stock (in shares)				29,544
Shares received in lieu of tax withholding payment on vested restricted stock				$ (854)			(854)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)				(11,424)
Stock-based compensation					2,472		2,472
Dividends						(4,163)	(4,163)
Share repurchase				$ (885)			(885)
Share repurchase (in shares)				(13,250)
BALANCE at Mar. 31, 2021			$ 411	$ (128,589)	326,143	525,138	723,103
BALANCE (in shares) at Mar. 31, 2021			41,123,365
BALANCE (in shares) at Mar. 31, 2021				(4,868,862)
BALANCE at Dec. 31, 2020			$ 411	$ (129,243)	322,451	502,810	$ 696,429
BALANCE (in shares) at Dec. 31, 2020			41,123,365				41,123,365
BALANCE (in shares) at Dec. 31, 2020				(4,935,186)			4,935,186
Increase (Decrease) in Stockholders' Equity
Net income							$ 105,753
BALANCE at Sep. 30, 2021			$ 411	$ (150,987)	326,493	595,872	$ 771,789
BALANCE (in shares) at Sep. 30, 2021			41,123,365				41,123,365
BALANCE (in shares) at Sep. 30, 2021				(5,080,907)			5,080,907
BALANCE at Mar. 31, 2021			$ 411	$ (128,589)	326,143	525,138	$ 723,103
BALANCE (in shares) at Mar. 31, 2021			41,123,365
BALANCE (in shares) at Mar. 31, 2021				(4,868,862)
Increase (Decrease) in Stockholders' Equity
Net income						32,965	32,965
Issuance of Stock:
Issuance of shares for options exercised				$ 1,853	191		2,044
Issuance of shares for options exercised (in shares)				69,342
Issuance of restricted stock & performance stock				$ 1,904	(1,904)
Issuance of restricted stock & performance stock (in shares)				71,816
Shares received in lieu of tax withholding payment on vested restricted stock				$ (1,509)			(1,509)
Shares received in lieu of tax withholding payment on vested restricted stock (in shares)				(19,989)
Stock-based compensation					1,749		1,749
Dividends						(4,178)	(4,178)
Share repurchase				$ (2,162)			(2,162)
Share repurchase (in shares)				(27,092)
BALANCE at Jun. 30, 2021			$ 411	$ (128,503)	326,179	553,925	752,012
BALANCE (in shares) at Jun. 30, 2021			41,123,365
BALANCE (in shares) at Jun. 30, 2021				(4,774,785)
Increase (Decrease) in Stockholders' Equity
Net income						46,297	46,297
Issuance of Stock:
Stock-based compensation					314		314
Dividends						(4,350)	(4,350)
Share repurchase				$ (22,484)			(22,484)
Share repurchase (in shares)				(306,122)
BALANCE at Sep. 30, 2021			$ 411	$ (150,987)	$ 326,493	$ 595,872	$ 771,789
BALANCE (in shares) at Sep. 30, 2021			41,123,365				41,123,365
BALANCE (in shares) at Sep. 30, 2021				(5,080,907)			5,080,907