Note 5 - Fair Value of Financial Instruments (Details Textual) BTU in Millions, $ in Millions				1 Months Ended
	Jan. 12, 2017 USD ($) BTU $ / item	Feb. 24, 2016 USD ($) Boe $ / item	Feb. 02, 2016 USD ($) BTU $ / item	Mar. 31, 2016 Boe $ / item	Feb. 28, 2016 $ / item
Derivative, Number of Options Rolled				2
Henry Hub Natural Gas Future ("NG") Contracts [Member] | Put Option [Member]
Payments for Derivative Instrument, Investing Activities | $	$ 0.7
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU	4.1
Derivative, Price Risk Option Strike Price	3
Henry Hub Natural Gas Future ("NG") Contracts [Member] | Call Option [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			4.1
Derivative, Price Risk Option Strike Price			2
Proceeds from Derivative Instrument, Investing Activities | $			$ 1.9
Brent Oil Future Contracts [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | Boe		185,000
Brent Oil Future Contracts [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price		32.8
Brent Oil Future Contracts [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price		35.5
Brent Oil Future Contracts [Member] | Call Option [Member]
Proceeds from Derivative Instrument, Investing Activities | $		$ 1.1
Rolled Two Existing Options [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | Boe				31,800
Rolled Two Existing Options [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price				41
Rolled Two Existing Options [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price				42.5
Before Rolling Two Existing Options [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price					32.8
Before Rolling Two Existing Options [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price					33.5
Short Risk Reversal Transactions, Rolling Existing Call Option 1 [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | Boe				16,500
Short Risk Reversal Transactions, Rolling Existing Call Option 1 [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price				28.5
Short Risk Reversal Transactions, Rolling Existing Call Option 1 [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price				37.5
Short Risk Reversal Transactions, Rolling Existing Call Option 2 [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | Boe				17,000
Short Risk Reversal Transactions, Rolling Existing Call Option 2 [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price				28
Short Risk Reversal Transactions, Rolling Existing Call Option 2 [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price				38.5