Note 2 - Summary of Significant Accounting Policies - Concentration Risk (Details) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2017
Revenue, related parties	$ 4,845,624	$ 6,472,531	$ 10,003,572	$ 12,840,475
Accounts receivable, related parties	1,602,428		1,602,428		$ 1,762,271
Wainwright [Member]
Revenue, related parties	4,800,000	6,500,000	10,000,000	12,800,000
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member]
Revenue, related parties	$ 4,845,624		$ 10,003,572	$ 12,840,475
Concentration risk percentage	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	$ 2,499,615		$ 5,443,460	$ 7,303,214
Concentration risk percentage	52.00%		54.00%	57.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member] | Customers Related to the USCI Fund [Member]
Revenue, related parties	$ 979,375		$ 1,957,993	$ 2,696,650
Concentration risk percentage	20.00%		20.00%	21.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member] | Customers Related to the UNG Fund [Member]
Revenue, related parties	$ 874,162		$ 1,572,018	$ 1,718,109
Concentration risk percentage	18.00%		16.00%	13.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Wainwright [Member] | All Other Customers [Member]
Revenue, related parties	$ 492,472		$ 1,030,101	$ 1,122,502
Concentration risk percentage	10.00%		10.00%	9.00%
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member]
Revenue, related parties		$ 6,472,531
Concentration risk percentage		100.00%	100.00%		100.00%
Accounts receivable, related parties	$ 1,602,428		$ 1,602,428		$ 1,762,271
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member] | Customers Related to the USO Fund [Member]
Revenue, related parties		$ 3,683,953
Concentration risk percentage		57.00%	50.00%		60.00%
Accounts receivable, related parties	799,623		$ 799,623		$ 1,060,421
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member] | Customers Related to the USCI Fund [Member]
Revenue, related parties		$ 1,323,374
Concentration risk percentage		20.00%	20.00%		18.00%
Accounts receivable, related parties	326,005		$ 326,005		$ 317,032
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member] | Customers Related to the UNG Fund [Member]
Revenue, related parties		$ 894,996
Concentration risk percentage		14.00%	20.00%		12.00%
Accounts receivable, related parties	312,466		$ 312,466		$ 217,760
Customer Concentration Risk [Member] | Accounts Receivable [Member] | Wainwright [Member] | All Other Customers [Member]
Revenue, related parties		$ 570,208
Concentration risk percentage		9.00%	10.00%		10.00%
Accounts receivable, related parties	$ 164,334		$ 164,334		$ 167,058