Note 5 - Fair Value of Financial Instruments (Details Textual) BTU in Millions, $ in Millions				1 Months Ended		2 Months Ended	3 Months Ended
	Mar. 24, 2016 Boe $ / item	Feb. 24, 2016 BTU $ / item	Mar. 06, 2014 BTU $ / item	Mar. 31, 2016 USD ($) Boe $ / item	Mar. 31, 2016 USD ($) $ / item	Mar. 31, 2016 USD ($) $ / item	Mar. 31, 2016 USD ($) $ / item	Mar. 31, 2015 USD ($)	Feb. 28, 2016 $ / item
NGI Swap Contract [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU			2.2
Underlying, Derivative Energy Measure			4.95
Henry Hub Natural Gas Future ("NG") Contracts [Member] | Call Option [Member]
Proceeds from Derivative Instrument, Investing Activities | $						$ 1.9
Henry Hub Natural Gas Future ("NG") Contracts [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU		4.1
Derivative, Price Risk Option Strike Price		2
Brent Oil Future Contracts [Member] | Call Option [Member]
Proceeds from Derivative Instrument, Investing Activities | $					$ 1.1
Brent Oil Future Contracts [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price	32.75
Brent Oil Future Contracts [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price	35.5
Brent Oil Future Contracts [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | Boe	185,000
Rolled Two Existing Options [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price				41	41	41	41
Rolled Two Existing Options [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price				42.5	42.5	42.5	42.5
Rolled Two Existing Options [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | Boe				31,800
Before Rolling Two Existing Options [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price									33
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] | Minimum [Member]
Derivative, Price Risk Option Strike Price				28.5	28.5	28.5	28.5
Short Risk Reversal Transactions, Rolling Existing Call Option 1 [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price				37.5	37.5	37.5	37.5
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 2 [Member] | Minimum [Member]
Derivative, Price Risk Option Strike Price				28	28	28	28
Short Risk Reversal Transactions, Rolling Existing Call Option 2 [Member] | Maximum [Member]
Derivative, Price Risk Option Strike Price				38.5	38.5	38.5	38.5
Short Risk Reversal Transactions, Rolling Existing Call Option 2 [Member]
Derivative, Nonmonetary Notional Amount, Energy Measure | Boe				17,000
Short Risk Reversal Transactions [Member]
Payments of Derivative Issuance Costs | $				$ 0.3
Derivative, Number of Options Rolled				2
Gain (Loss) on Price Risk Derivative Instruments Not Designated as Hedging Instruments | $							$ (0.1)	$ 0.3