Goodwill (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	Nov. 30, 2015	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Beginning Balance			$ 596,316	$ 553,335
Goodwill, Acquired During Period			220,795	57,992
Goodwill, Translation Adjustments			(15,705)	(15,011)
Ending Balance		$ 801,406	801,406	596,316
DVTEL [Member]
Goodwill [Roll Forward]
Beginning Balance			$ 60,494
Goodwill, Acquired During Period	$ 58,000	$ 2,500
Ending Balance				$ 60,494