CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Total
Balance at Dec. 31, 2016		$ 412,726	$ 11,407	$ 126,462	$ (16,717)	$ (2,846)	$ 531,032
Net income				11,880			11,880
Other comprehensive income, net of tax						(441)	(441)
Cash dividends declared on common stock ($0.075 per share)				(2,403)			(2,403)
Stock issuance costs		(180)					(180)
Restricted stock grants (56,164 and 22,004 shares)
Stock-based compensation			389				389
Balance at Mar. 31, 2017		412,546	11,796	135,939	(16,717)	(3,287)	540,277
Balance at Dec. 31, 2017		412,546	13,602	160,025	(16,717)	(4,019)	565,437
Reclassification of stranded tax effects (ASU 2018-02) (see Note 8)				709		(709)
Cumulative effect of adopting ASU 2016-01 (see Note 8)				(55)		55
Net income				4,251			4,251
Other comprehensive income, net of tax						(2,834)	(2,834)
Cash dividends declared on common stock ($0.075 per share)				(2,420)			(2,420)
Exercise of stock options (38,697 shares)			202				202
Restricted stock grants (56,164 and 22,004 shares)
Net performance units issued (42,672 shares)			(819)				(819)
Stock-based compensation			449				449
Balance at Mar. 31, 2018		$ 412,546	$ 13,434	$ 162,510	$ (16,717)	$ (7,507)	$ 564,266