Acquisitions (Cash Paid for Acquisitions) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Combinations [Abstract]
Cash paid for acquisitions completed during the year	$ 196,395	$ 70,948	$ 17,284
Cash paid for holdback payments during the year	3,404	3,060	828
Earn-out and other payments during the year	1,453	3,610	50
Total cash paid for acquisitions	$ 201,252	$ 77,618	$ 18,162