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Retirement Savings Plan - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer matching contributions vesting period | 2 years |  |
United States |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer matching contributions | $ 579 us-gaap_DefinedBenefitPlanContributionsByEmployer / us-gaap_StatementGeographicalAxis = country_US | $ 1,000 us-gaap_DefinedBenefitPlanContributionsByEmployer / us-gaap_StatementGeographicalAxis = country_US | $ 1,200 us-gaap_DefinedBenefitPlanContributionsByEmployer / us-gaap_StatementGeographicalAxis = country_US
Canada |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Employer matching contributions | $ 26 us-gaap_DefinedBenefitPlanContributionsByEmployer / us-gaap_StatementGeographicalAxis = country_CA | $ 157 us-gaap_DefinedBenefitPlanContributionsByEmployer / us-gaap_StatementGeographicalAxis = country_CA | $ 232 us-gaap_DefinedBenefitPlanContributionsByEmployer / us-gaap_StatementGeographicalAxis = country_CA

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- Definition Defined contribution plan employers matching contribution vesting period. + References No definition available. + Details
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- Definition The increase in the fair value of plan assets from contributions made by the employer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920 + Details
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