| Income Taxes - Summary of deferred tax assets and liabilities (Details 3) - USD ($) $ in Thousands | Dec. 31, 2018 | Dec. 31, 2017 | 
|---|---|---|
| Deferred tax assets: | ||
| Deferred rent liabilities | $ 2,524 | $ 2,637 | 
| Lease incentives | 1,577 | 1,484 | 
| Stock compensation | 417 | 458 | 
| FICA tip credit carryforward | 4,255 | 3,224 | 
| Net operating loss | 3,705 | 5,129 | 
| Goodwill | 1,652 | 1,839 | 
| Inventory | 12 | 13 | 
| Charitable contributions carryforward | 39 | 37 | 
| Foreign tax credit carryforward | 336 | 566 | 
| Deferred revenue | 335 | 383 | 
| State and local tax credit carryforward | 445 | 346 | 
| Expenses not deductible until paid | 283 | 0 | 
| Total deferred tax assets | 15,580 | 16,116 | 
| Deferred tax liabilities: | ||
| Depreciation and amortization | (4,031) | (3,661) | 
| Basis in LLC interest | (526) | (592) | 
| ASC 740-10 liability | (190) | (233) | 
| Total deferred tax liabilities | (4,747) | (4,486) | 
| Valuation allowance | (10,795) | (11,561) | 
| Net deferred tax assets | $ 38 | $ 69 | 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences for lease incentives. No definition available. 
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- Definition Deferred Tax Assets, Tax Credit Carryforwards, State and Local No definition available. 
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- Definition Deferred Tax Liabilities, Uncertain Tax Positions No definition available. 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible charitable contribution carryforwards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from deferred income. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from intangible assets including goodwill. No definition available. 
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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://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from inventory. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- References No definition available. 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible foreign tax credit carryforwards. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible tax credit carryforwards, classified as other. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount, before allocation of valuation allowances, of deferred tax asset attributable to deductible differences from reserves and accruals, compensation and benefit costs, and other provisions, reserves, and allowances. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from share-based compensation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from deferred rent. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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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://fasb.org/us-gaap/role/ref/legacyRef 
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- References No definition available. 
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- Definition Amount of deferred tax liability attributable to taxable temporary differences from investments (excludes investments in subsidiaries and equity method investments). No definition available. 
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| X | ||||||||||
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- Definition Amount of deferred tax liability attributable to taxable temporary differences from property, plant, and equipment. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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