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Employee Benefit Plan - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
United States [Member]
Schedule Of Pension And Other Postretirement Benefits Expected Benefit Payments [Line Items]
Contribution pension plan	$ 119us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount / us-gaap_StatementGeographicalAxis = country_US	$ 116us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount / us-gaap_StatementGeographicalAxis = country_US	$ 111us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount / us-gaap_StatementGeographicalAxis = country_US
Belgium [Member]
Schedule Of Pension And Other Postretirement Benefits Expected Benefit Payments [Line Items]
Contribution pension plan	$ 697us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount / us-gaap_StatementGeographicalAxis = country_BE	$ 655us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount / us-gaap_StatementGeographicalAxis = country_BE	$ 542us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount / us-gaap_StatementGeographicalAxis = country_BE

X

- Definition

Amount of discretionary contributions made by an employer to a defined contribution plan.

+ References

No definition available.

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X

- Details

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X

- Details

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