Quarterly report pursuant to Section 13 or 15(d)

Note 7 - Fair Value Measurements (Details Textual)

v3.10.0.1
Note 7 - Fair Value Measurements (Details Textual)
$ in Millions
9 Months Ended
Sep. 30, 2018
USD ($)
Jun. 30, 2018
Impairment of Long-Lived Assets Held-for-use $ 3.0  
Debt Instrument, Interest Rate, Stated Percentage   2.00%
Minimum [Member] | Economic Obsolesence Factor [Member]    
Property and Equipment, Measurement Input 0.45  
Maximum [Member] | Economic Obsolesence Factor [Member]    
Property and Equipment, Measurement Input 0.5  
Liftboats [Member] | Minimum [Member]    
Property, Plant and Equipment, Useful Life 25 years  
Liftboats [Member] | Maximum [Member]    
Property, Plant and Equipment, Useful Life 40 years