Note 2 - Summary of Significant Accounting Policies - Concentration Risk (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Jun. 30, 2018
Revenue, related parties	$ 3,939,004	$ 4,845,624	$ 8,161,988	$ 10,003,572
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member]
Revenue, related parties	$ 3,939,004	$ 4,845,624	$ 8,161,988	$ 10,003,572
Concentration risk percentage	100.00%	100.00%	100.00%	100.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member] | Customers Related to the USO Fund [Member]
Revenue, related parties	$ 1,853,481	$ 2,499,615	$ 3,838,402	$ 5,443,460
Concentration risk percentage	47.00%	52.00%	47.00%	54.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member] | Customers Related to the USCI Fund [Member]
Revenue, related parties	$ 1,095,830	$ 979,375	$ 2,349,689	$ 1,957,993
Concentration risk percentage	28.00%	20.00%	29.00%	20.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member] | Customers Related to the UNG Fund [Member]
Revenue, related parties	$ 572,526	$ 874,162	$ 1,077,388	$ 1,572,018
Concentration risk percentage	14.00%	18.00%	13.00%	16.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member] | All Other Customers [Member]
Revenue, related parties	$ 417,167	$ 492,472	$ 896,509	$ 1,030,101
Concentration risk percentage	11.00%	10.00%	11.00%	10.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member]
Revenue, related parties			$ 1,231,782		$ 1,458,159
Concentration risk percentage			100.00%		100.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member] | Customers Related to the USO Fund [Member]
Revenue, related parties			$ 583,979		$ 674,535
Concentration risk percentage			47.00%		46.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member] | Customers Related to the USCI Fund [Member]
Revenue, related parties			$ 334,497		$ 431,288
Concentration risk percentage			27.00%		30.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member] | Customers Related to the UNG Fund [Member]
Revenue, related parties			$ 180,633		$ 182,399
Concentration risk percentage			15.00%		12.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member] | All Other Customers [Member]
Revenue, related parties			$ 132,673		$ 169,937
Concentration risk percentage			11.00%		12.00%