Changes in Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Feb. 01, 2019
Movement in Deferred Revenue [Roll Forward]
Beginning balance	$ 343,174	$ 299,730
Acquired deferred revenue	2,349	0	$ 2,349
Deferral of revenue	318,279	307,978
Recognition of revenue	(317,130)	(282,873)
Currency translation	(2,396)	4,559
Ending balance	$ 344,276	$ 329,394

Amount of deferred revenue expected to be recognized as such within one year or the normal operating cycle, if longer, assumed at the acquisition date.

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- Definition

Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable.

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Amount of deferred revenue recognized for transactions arising during the current reporting period. Deferred revenue is a liability as of the balance sheet date related to a revenue producing activity for which revenue has not yet been recognized. Generally, an Entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP.

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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 of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Amount of cumulative translation gain (loss), before tax, from translating foreign currency financial statements into the reporting currency.

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