Acquisitions Of Businesses (Details) $ in Thousands								12 Months Ended
	Oct. 19, 2015 Company	Oct. 13, 2015 Company	Jun. 01, 2015 Company	Dec. 02, 2013 Company	Jul. 29, 2013 USD ($)	Jul. 29, 2013 USD ($) Company	May. 31, 2013 Company	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Business Acquisition [Line Items]
Business acquisition date	Oct. 19, 2015	Oct. 13, 2015	Jun. 01, 2015	Dec. 02, 2013			May 31, 2013
Proceeds from revolving credit facility								$ 0	$ 0	$ 250,000
Goodwill								843,170	834,102	834,825
Number of businesses acquired | Company	1	1	1	1		1	1
Non-cash (income) expense from contingent consideration arrangements								$ (464)	$ 606	$ (6,793)
RepconStrickland
Business Acquisition [Line Items]
Business acquisition date						Jul. 29, 2013
Business acquisition, percentage of voting interests acquired					100.00%	100.00%
Purchase price					$ 463,600
Proceeds from revolving credit facility					250,000
Working capital acquired					35,500	$ 35,500
Other net liabilities acquired					67,100	67,100
Goodwill					267,800	267,800
Identifiable intangible assets					227,400	227,400
Acquired goodwill, tax deductible amount					$ 49,000	$ 49,000