CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2014	$ 11,250	$ 374,287	$ 6,015	$ 72,398	$ (16,717)	$ (1,014)	$ 446,219
Net income				31,743			31,743
Other comprehensive loss, net of tax						(2,296)	(2,296)
Dividend on series B preferred stock				(84)			(84)
Cash dividends declared on common stock ($0.15 per share)				(6,736)			(6,736)
Exercise of stock options			1,424				1,424
Restricted stock and performance units grants
Stock-based compensation expense			876				876
Balance at Sep. 30, 2015	11,250	374,287	8,315	97,321	(16,717)	(3,310)	471,146
Balance at Dec. 31, 2015	11,250	374,287	8,527	104,606	(16,717)	(4,609)	477,344
Net income				33,106			33,106
Other comprehensive loss, net of tax						5,333	5,333
Dividend on series B preferred stock				(22)			(22)
Cash dividends declared on common stock ($0.15 per share)				(6,805)			(6,805)
Redemption of preferred stock	(11,250)						(11,250)
Exercise of stock options			232				232
Restricted stock and performance units grants
Stock-based compensation expense			1,650				1,650
Balance at Sep. 30, 2016		$ 374,287	$ 10,409	$ 130,885	$ (16,717)	$ 724	$ 499,588