Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance		$ 2,679,800
Ending Balance	$ 3,112,500	3,112,500
Foreign currency
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(45,387)	(47,966)
Other comprehensive income (loss) before reclassifications	14,347	16,926
Net decrease (increase) in other comprehensive loss	14,347	16,926
Ending Balance	(31,040)	(31,040)
Change in unrealized gains on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(472)	(599)
Other comprehensive income (loss) before reclassifications	144	271
Net decrease (increase) in other comprehensive loss	144	271
Ending Balance	(328)	(328)
AOCI Attributable to Parent
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning Balance	(45,859)	(48,565)
Other comprehensive income (loss) before reclassifications	14,491	17,197
Net decrease (increase) in other comprehensive loss	14,491	17,197
Ending Balance	$ (31,368)	$ (31,368)