Income Taxes - Significant Components of Company's Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands  | 
Dec. 31, 2017  | 
Dec. 31, 2016  | 
|---|---|---|
| Deferred Tax Assets: | ||
| Asset Reserves | $ 5,615 | $ 9,208 | 
| Deferred Compensation | 6,091 | 8,378 | 
| Capital Lease Basis Difference | 1,002 | 1,690 | 
| State Investment and Research and Development Tax Credit Carryforwards, Net of Federal Tax | 1,379 | 665 | 
| Customer Advanced Payments and Deferred Revenue | 1,007 | 3,750 | 
| State Net Operating Loss Carryforwards and Other | 8,115 | 4,282 | 
| Total Gross Deferred Tax Assets | 23,209 | 27,973 | 
| Valuation Allowance for Foreign Tax Credit, State Deferred Tax Assets and Tax Credit Carryforwards, Net of Federal Tax | (7,823) | (3,816) | 
| Deferred Tax Assets | 15,386 | 24,157 | 
| Deferred Tax Liabilities: | ||
| Depreciation | 9,267 | 12,972 | 
| Goodwill and Intangible Assets | 7,275 | 18,558 | 
| Other | 1,149 | 1,280 | 
| Deferred Tax Liabilities | 17,691 | 32,810 | 
| Net Deferred Tax Liabilities | $ (2,305) | $ (8,653) | 
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- Definition Capital Lease Assets Basis Difference No definition available. 
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- Definition Deferred tax assets customer advanced payments and deferred revenue. No definition available. 
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- References No definition available. 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount after allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible state and local operating loss carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible general business tax credit carryforwards. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from compensation and benefits costs. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible temporary differences from reserves, classified as other. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences without jurisdictional netting. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- References No definition available. 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences from intangible assets including goodwill. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences classified as other. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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