Goodwill (Details)	6 Months Ended
Jun. 30, 2018 USD ($)
Goodwill [Roll Forward]
Balance as of December 31, 2017	$ 210,885,000
Foreign currency translation adjustments	(498,000)
Balance as of June 30, 2018	210,387,000
Goodwill impairment	$ 0

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.

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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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