Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands		Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Deferred Compensation [Member]	Treasury Stock [Member]
Beginning Balances (shares) at Dec. 31, 2014	[1]		14,588,711
Beginning Balances at Dec. 31, 2014		$ 300,322	$ 7,100	$ 156,581	$ 142,317	$ (5,676)	$ 1,258	$ (1,258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		41,140			41,140
Other comprehensive loss		(164)				(164)
Dividend declared ($1.1325 per share)		(17,222)			(17,222)
Retirement savings plan and dividend reinvestment plan (shares)			43,275
Retirement savings plan and dividend reinvestment plan		2,235	$ 21	2,214
Common stock issued in acquisition (shares)			592,970
Common stock issued in acquisition		30,165	$ 289	29,876
Share-based compensation (shares)	[1],[2],[3]		45,703
Share-based compensation and tax benefit	[2],[3]	1,662	$ 22	1,640
Treasury stock activities		0					625	(625)
Ending Balances (shares) at Dec. 31, 2015	[1]		15,270,659
Ending Balances at Dec. 31, 2015		358,138	$ 7,432	190,311	166,235	(5,840)	1,883	(1,883)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income		28,396			28,396
Other comprehensive loss		672				672
Dividend declared ($0.2875 per share) and dividend reinvestment plan (shares)			13,120
Dividend declared ($0.5925 per share) and dividend reinvestment plan		(8,376)	$ 6	759	(9,141)
Share-based compensation (shares)	[1],[2],[3]		36,099
Share-based compensation and tax benefit	[2],[3]	724	$ 18	706
Treasury stock activities		0					569	(569)
Ending Balances (shares) at Jun. 30, 2016	[1]		15,319,878
Ending Balances at Jun. 30, 2016		$ 379,554	$ 7,456	$ 191,776	$ 185,490	$ (5,168)	$ 2,452	$ (2,452)

[1] Includes 79,658 and 70,631 shares at June 30, 2016 and December 31, 2015, respectively, held in a Rabbi Trust related to our Deferred Compensation Plan.

[2] Includes amounts for shares issued for Directors’ compensation.

[3] The shares issued under the SICP are net of shares withheld for employee taxes. For the six months ended June 30, 2016, and for the year ended December 31, 2015, we withheld 12,031 and 12,620 shares, respectively, for taxes.