Note 9 - Long-term Incentive Plan - Period and Predetermined Stock Price Needed for Vesting (Details)	6 Months Ended
	Jun. 30, 2017 $ / shares
Share-based Compensation Award, Tranche One [Member]
Ends Vesting	48 months after Grant Dates
Predetermined Vesting Price (in dollars per share)	$ 3.43
Begins Vesting	12 months after Grant Dates
Share-based Compensation Award, Tranche Two [Member]
Ends Vesting	60 months after Grant Dates
Predetermined Vesting Price (in dollars per share)	$ 4.69
Begins Vesting	24 months after Grant Dates
Share-based Compensation Award, Tranche Three [Member]
Ends Vesting	72 months after Grant Dates
Predetermined Vesting Price (in dollars per share)	$ 6.43
Begins Vesting	36 months after Grant Dates
Share-Based Compensation Award Tranche Four [Member]
Ends Vesting	84 months after Grant Dates
Predetermined Vesting Price (in dollars per share)	$ 8.81
Begins Vesting	48 months after Grant Dates
Share-Based Compensation Award Tranche Five [Member]
Ends Vesting	96 months after Grant Dates
Predetermined Vesting Price (in dollars per share)	$ 12.07
Begins Vesting	60 months after Grant Dates