Income Taxes - Summary of Activity Related to Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance as of January 1	$ 824	$ 3,087	$ 2,797
Increases related to prior year tax positions	0	0	156
Decreases related to prior year tax positions	(320)	(2,520)	0
Increases related to current year tax positions	300	169	178
Effect of exchange rate changes, increase	0	88
Effect of exchange rate changes, decrease			44
December 31	$ 804	$ 824	$ 3,087

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

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Amount of decrease in unrecognized tax benefits resulting from foreign currency translation.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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Amount of increase in unrecognized tax benefits resulting from foreign currency translation.

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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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