Acquisitions (Details) (USD $)	12 Months Ended			0 Months Ended	12 Months Ended
	Dec. 31, 2013 item	Dec. 31, 2012	Dec. 31, 2011	Nov. 02, 2011 EAS	Dec. 31, 2012 Other Acquisitions	Dec. 31, 2011 Other Acquisitions
Acquisitions
Interest acquired (as a percent)				60.00%
Number of acquisitions	0
Fair value of consideration transferred				$ 30,400,000	$ 14,200,000	$ 2,900,000
Goodwill on acquisition	$ 114,588,000	$ 114,588,000	$ 107,093,000	$ 15,700,000