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% |