Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Treasury Stock [Member]
Beginning balance at Dec. 31, 2013	$ 230,183	$ 400	$ 14,157	$ 158,650	$ 73,491	$ (16,515)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	15,526	0	0	0	15,526	0
Other comprehensive income	6,432	0	0	0	0	6,432
Dividends declared on preferred stock	(60)	0	0	0	(60)	0
Common stock issued under stock option plans, including tax benefit	694	0	47	647	0	0
Common stock issued under employee stock purchase plan	0	0	0	0	0	0
Proceeds from issuance of common stock in connection with dividend reinvestment and stock purchase plan	43	0	2	41	0	0
Common stock share-based awards	544	0	0	544	0	0
Ending balance at Sep. 30, 2014	253,362	400	14,206	159,882	88,957	(10,083)	0
Beginning balance at Dec. 31, 2014	265,523	400	14,233	160,588	94,496	(3,875)	(319)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	14,714	0	0	0	14,714	0
Other comprehensive income	2,304	0	0	0	0	2,304
Dividends declared on preferred stock	(60)	0	0	0	(60)	0
Dividends declared on common stock	(2,970)	0	0	0	(2,970)	0
Common stock issued under stock option plans, including tax benefit	3,718	0	199	3,519	0	0
Common stock issued under employee stock purchase plan	2	0	0	2	0	0
Proceeds from issuance of common stock in connection with dividend reinvestment and stock purchase plan	45	0	2	43	0	0
Common stock share-based awards	1,734	0	0	1,734	0	0
Purchase of shares of treasury stock	(7,412)						(7,412)
Ending balance at Sep. 30, 2015	$ 277,598	$ 400	$ 14,434	$ 165,886	$ 106,180	$ (1,571)	$ (7,731)