| INCOME TAXES Components of Net Deferred Tax Liabilities (Details) - USD ($) $ in Thousands | Dec. 31, 2019 | Dec. 31, 2018 | 
|---|---|---|
| Deferred tax liabilities: | ||
| Property and equipment | $ 111,411 | $ 116,178 | 
| Buy-in on maintenance contracts | 223 | 423 | 
| Total deferred tax liabilities | 111,634 | 116,601 | 
| Deferred tax assets: | ||
| Tax loss carryforwards | 47,243 | 44,919 | 
| Stock compensation | 690 | 691 | 
| Reserves | 742 | 788 | 
| Other | 658 | (285) | 
| Valuation allowance | (41,492) | (37,869) | 
| Total deferred tax assets | 7,841 | 8,244 | 
| Net deferred tax liabilities | $ 103,793 | $ 108,357 | 
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- Definition Deferred Tax Liabilities, Other, Buy-in on Maintenance Programs 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 after 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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- 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 allowance, of deferred tax asset attributable to deductible temporary differences, 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 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 allowance, of deferred tax asset attributable to deductible temporary differences from reserves, classified as other. 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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- Definition Amount, after deferred tax asset, of deferred tax liability attributable to taxable differences 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 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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