Goodwill and Identifiable Intangible Assets - Activity in Goodwill Balance (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Goodwill [Roll Forward]
Balance at beginning of period	$ 865,527	$ 882,884	$ 868,126		$ 868,126
Effect of foreign currency translation	(23,260)	(17,357)	14,758
Goodwill impairment	(10,718)			$ 0	(10,718)	$ 0
Balance at end of period	$ 831,549	$ 865,527	$ 882,884		$ 831,549

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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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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