Accumulated Other Comprehensive Income (Loss) (Details) $ in Thousands	9 Months Ended
Sep. 30, 2018 USD ($)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 1,476,839
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive loss before reclassifications	(8,923)
Amounts reclassified from accumulated other comprehensive loss	(32)
Net current-period other comprehensive loss	(8,955)
Ending balance	1,630,510
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(19,522)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive loss before reclassifications	(7,261)
Amounts reclassified from accumulated other comprehensive loss	0
Net current-period other comprehensive loss	(7,261)
Ending balance	(26,783)
Unrealized Gains (Losses) on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(386)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Other comprehensive loss before reclassifications	(1,662)
Amounts reclassified from accumulated other comprehensive loss	(32)
Net current-period other comprehensive loss	(1,694)
Ending balance	(2,080)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(19,908)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Ending balance	$ (28,863)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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