Business Combination - Summary of Operating Results of ETFS since the Acquisition Date (Detail) $ in Thousands	3 Months Ended
Mar. 31, 2018 USD ($)
Business Combinations [Abstract]
Revenues	$ 79,771
Net income	11,243
Proforma loss on revaluation of deferred consideration	$ (2,555)

This element represents the amount of earnings or loss of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)
-URI http://asc.fasb.org/extlink&oid=79982066&loc=d3e1392-128463

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- Definition

This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

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- References

No definition available.

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- Definition

Proforma gain (loss) from revaluation of deferred consideration.

+ References

No definition available.

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