Intangible Assets Summary of Intangible Asset Account Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Total Intangible Assets [Abstract]
Beginning balance, Finite-Lived Intangible Assets, Gross	$ 669,896	$ 702,507
Intangible assets acquired	36,500	0
Effect of change in exchange rates	63,455	(32,611)
Ending balance, Finite-Lived Intangible Assets, Gross	$ 769,851	$ 669,896