Acquisitions (Details) (USD $)			3 Months Ended
	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2014 Series of Business Acquisitions company
Business Acquisition [Line Items]
Number of companies acquired			3
Aggregate purchase price			$ 38,900,000
Additional purchase amount to be paid in third quarter			500,000
Goodwill	$ 273,176,000	$ 231,838,000	$ 41,300,000