Note 9 - Leases (Details Textual) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| Operating Leases, Rent Expense, Net | $ 1.0 | $ 1.0 |
| Pump Assets [Member] | ||
| Capital Leased Assets, Gross | 14.0 | 13.9 |
| Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation | $ 6.1 | $ 4.2 |
| Capital Leases [Member] | ||
| Debt, Weighted Average Interest Rate | 3.60% | |
| X | ||||||||||
- Definition Amount before accumulated depreciation of leased physical assets used in the normal conduct of business to produce goods and services. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition The total charge for the use of long-lived depreciable assets subject to a lease meeting the criteria for capitalization. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Definition Weighted average interest rate of debt outstanding. No definition available.
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| X | ||||||||||
- Definition Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
- Details
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| X | ||||||||||
- Details
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