Consolidated Statements of Stockholders' Equity (Unaudited) (USD $) In Thousands, except Share data	Total USD ($)	Common Stock Outstanding	Common Stock USD ($)	Value of Shares Held in Rabbi Trust at Cost USD ($)	Deferred Compensation and Other Retirement Benefit Obligations USD ($)	Additional Paid in Capital USD ($)	Retained Earnings USD ($)	Accumulated Other Comprehensive Loss USD ($)
Balance March 31, 2015 at Dec. 31, 2013	$ 591,540		$ 235	$ (3,404)	$ 3,404	$ 305,179	$ 293,560	$ (7,434)
Balance March 31, 2015 at Dec. 31, 2013		23,805,984
Net income	13,383						13,383
Other comprehensive income	2,380							2,380
Common dividend declared ($0.26 per share)	(5,725)						(5,725)
Stock Issued During Period, Value, Acquisitions	0
Common stock issued for acquisition		7,911
Common stock issued for acquisition	133					133
Proceeds from exercise of stock options, net of cash paid	193					193
Tax benefit related to equity award activity	677					677
Stock based compensation		55,761
Stock based compensation	(472)		1			(473)
Stock Issued During Period, Shares, Other		8,400
Stock Issued During Period, Value, Other	319					319
Increase (Decrease) in Deferred Compensation				(52)	52
Deferred compensation and other retirement benefit obligations	128					128
Tax benefit related to deferred compensation distributions at Mar. 31, 2014	602,556		236	(3,456)	3,456	306,156	301,218	(5,054)
Tax benefit related to deferred compensation distributions at Mar. 31, 2014		23,878,056
Balance March 31, 2015 at Dec. 31, 2014	640,527		237	(3,666)	3,666	311,978	330,444	(2,132)
Balance March 31, 2015 at Dec. 31, 2014	23,998,738	23,998,738
Net income	9,460						9,460
Other comprehensive income	1,719							1,719
Common dividend declared ($0.26 per share)	(6,800)						(6,800)
Stock Issued During Period, Shares, Acquisitions		2,052,137
Stock Issued During Period, Value, Acquisitions	86,415		21			86,394
Common stock issued for acquisition		23,436
Common stock issued for acquisition	321					321
Proceeds from exercise of stock options, net of cash paid	337					337
Tax benefit related to equity award activity	739					739
Stock based compensation		33,491
Stock based compensation	(635)		1			(636)
Stock Issued During Period, Shares, Other		15,774
Stock Issued During Period, Value, Other	638					638
Increase (Decrease) in Deferred Compensation and Other Retirement Benefits				(34)	34
Deferred compensation and other retirement benefit obligations	165					165
Tax benefit related to deferred compensation distributions at Mar. 31, 2015	$ 732,886		$ 259	$ (3,700)	$ 3,700	$ 399,936	$ 333,104	$ (413)
Tax benefit related to deferred compensation distributions at Mar. 31, 2015	26,123,576	26,123,576