Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Capital Surplus [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss), Net of Tax [Member]	Total
Balance at Dec. 31, 2012	$ 78,065	$ 160,670	$ 148,944	$ 12,665	$ 400,344
Balance (in shares) at Dec. 31, 2012	17,174,231
Increase (Decrease) in Stockholders' Equity [Roll forward]
Net income			45,172		45,172
Other comprehensive income (loss), net of tax				(20,691)	(20,691)
Cash dividends declared			(19,827)		(19,827)
Issuance of common stock	$ 1,038	5,310			6,348
Issuance of common stock (in shares)	228,260
Issuance of restricted stock	$ 4	(4)			0
Issuance of restricted stock (in shares)	950
Stock-based compensation and related excess tax benefits		1,146			1,146
Balance at Dec. 31, 2013	$ 79,107	167,122	174,289	(8,026)	412,492
Balance (in shares) at Dec. 31, 2013	17,403,441
Increase (Decrease) in Stockholders' Equity [Roll forward]
Net income			43,251		43,251
Other comprehensive income (loss), net of tax				9,190	9,190
Cash dividends declared			(20,539)		(20,539)
Issuance of 10% stock dividend	$ 7,910	44,394	(52,304)		0
Issuance of common stock	$ 346	1,646			1,992
Issuance of common stock (in shares)	69,138
Vesting of restricted stock	$ (45)	45			0
Vesting of restricted stock (in shares)	(8,945)
Issuance of restricted stock	$ 23	(23)			0
Issuance of restricted stock (in shares)	4,576
Forfeiture of restricted stock	$ (9)	9			0
Forfeiture of restricted stock (in shares)	(1,835)
Stock-based compensation and related excess tax benefits		1,491			1,491
Balance at Dec. 31, 2014	$ 87,332	214,684	144,697	1,164	$ 447,877
Balance (in shares) at Dec. 31, 2014	17,466,375				17,466,375
Increase (Decrease) in Stockholders' Equity [Roll forward]
Net income			46,432		$ 46,432
Other comprehensive income (loss), net of tax				(153)	(153)
Cash dividends declared			(21,274)		(21,274)
Issuance of common stock	$ 564	1,518			2,082
Issuance of common stock (in shares)	112,837
Repurchase of common stock	$ (29)	(160)			(189)
Repurchase of common stock (in shares)	(5,724)
Vesting of restricted stock	$ (232)	232			0
Vesting of restricted stock (in shares)	(46,482)
Issuance of restricted stock	$ 53	(53)			0
Issuance of restricted stock (in shares)	10,582
Forfeiture of restricted stock	$ (3)	3			0
Forfeiture of restricted stock (in shares)	(674)
Stock-based compensation and related excess tax benefits		808			808
Balance at Dec. 31, 2015	$ 87,685	$ 217,032	$ 169,855	$ 1,011	$ 475,583
Balance (in shares) at Dec. 31, 2015	17,536,914				17,536,914