CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-In Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Total
Beginning balances at Dec. 31, 2017	$ 218	$ 177,498	$ 155,533	$ (68)	$ (9,104)	$ 324,077
Increase (Decrease) in Stockholders' Equity
Net income			22,463			22,463
Other comprehensive income (loss)					(1,245)
Share-based compensation		2,079
Stock option exercised and issuance of common stock and restricted common stock	2	1,121
Dividend paid			(7,884)
Repurchase of common stock				(313)
Issuance of restricted common stock from treasury shares		(11)		11
Ending balances at Jun. 30, 2018	220	180,687	170,112	(370)	(10,349)	340,300
Beginning balances at Mar. 31, 2018	219	178,840	160,838	(370)	(9,380)	330,147
Increase (Decrease) in Stockholders' Equity
Net income			13,220			13,220
Other comprehensive income (loss)					(969)
Share-based compensation		1,011
Stock option exercised and issuance of common stock and restricted common stock	1	836
Dividend paid			(3,946)
Ending balances at Jun. 30, 2018	220	180,687	170,112	(370)	(10,349)	340,300
Beginning balances at Dec. 31, 2018	220	183,834	189,324	(370)	(13,791)	$ 359,217
Balance (in shares) at Dec. 31, 2018						22,040,000
Increase (Decrease) in Stockholders' Equity
Net income			23,534			$ 23,534
Other comprehensive income (loss)					1,501
Share-based compensation		2,467
Stock option exercised and issuance of common stock and restricted common stock	1	(1,103)
Dividend paid			(7,942)
Repurchase of common stock				(916)
Issuance of restricted common stock from treasury shares		(451)		451
Issuance of restricted stock from treasury stock (in shares)						7,800
Ending balances at Jun. 30, 2019	221	184,747	204,916	(835)	(12,290)	$ 376,759
Balance (in shares) at Jun. 30, 2019						22,089,000
Beginning balances at Mar. 31, 2019	221	183,953	193,397	(1,286)	(12,793)	$ 363,492
Increase (Decrease) in Stockholders' Equity
Net income			15,491			15,491
Other comprehensive income (loss)					503
Share-based compensation		1,245
Dividend paid			(3,972)
Issuance of restricted common stock from treasury shares		(451)		451
Ending balances at Jun. 30, 2019	$ 221	$ 184,747	$ 204,916	$ (835)	$ (12,290)	$ 376,759
Balance (in shares) at Jun. 30, 2019						22,089,000