Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Total
Balance at Dec. 31, 2017	$ 315	$ 217,906	$ 381,048	$ (57,675)	$ (8,986)	$ 532,608
Net income			11,412			11,412
Award of common shares released from Employee Benefit Trust		2,488				2,488
Vesting of restricted stock unit awards		(4,731)	(170)	4,901
Stock-based compensation expense		3,452				3,452
Repurchase of shares to satisfy tax obligation				(2,050)		(2,050)
Dividends on common stock			(5,795)			(5,795)
Other comprehensive income (loss)					(895)	(895)
Reclassification of the Income tax effects of Tax Cuts and Jobs Act from AOCI to Retained Earnings			2,073		(2,073)
Impact of adoption of Accounting Standard Update 2016-01			(775)		775
Purchase of treasury shares				(5,913)		(5,913)
Balance at Mar. 31, 2018	315	219,115	387,793	(60,737)	(11,179)	535,307
Balance at Dec. 31, 2018	315	222,720	414,327	(75,146)	(12,752)	549,464
Impact of adoption of ASC 842 - Leases | Accounting Standards Update 2016-02 [Member]			2,716			2,716
Net income			7,068			7,068
Award of common shares released from Employee Benefit Trust		2,086				2,086
Vesting of restricted stock unit awards		(5,878)	(210)	6,088
Exercise of stock options			(3)	6		3
Stock-based compensation expense		3,931				3,931
Repurchase of shares to satisfy tax obligation				(1,877)		(1,877)
Dividends on common stock			(6,042)			(6,042)
Other comprehensive income (loss)					2,210	2,210
Reclassification of the Income tax effects of Tax Cuts and Jobs Act from AOCI to Retained Earnings
Balance at Mar. 31, 2019	$ 315	$ 222,859	$ 417,856	$ (70,929)	$ (10,542)	$ 559,559