Accumulated Other Comprehensive Income (Loss) - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net increase (decrease) in other comprehensive income (loss)	$ (10,944)	$ 19,402	$ (53,236)	$ 80,497
Currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Net increase (decrease) in other comprehensive income (loss)	$ (17,132)	$ 36,912	$ (80,870)	$ 142,248

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

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