Note 4 - Notes Receivable, Related Party (Details Textual) - USD ($)	1 Months Ended		3 Months Ended	6 Months Ended
	Apr. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017	May 31, 2017	Jun. 30, 2014
Proceeds from Sale of Variable Interest Entity Shares with Agreement to Repurchase				$ (250,000)	$ 125,000
Milestone China [Member]
Equity Method Investment, Ownership Percentage								40.00%
Equity Method Investment, Deferred Gain on Sale		$ 1,400,000
Equity Method Investments		$ 0	$ 0	0	0	$ 0		$ 1,000,000
Milestone China [Member] | Sale of Variable Interest Entity's Shares [Member]
Equity Method Investment, Ownership Percentage							40.00%
Option to Repurchase, Period		10 years
Price for Shares of Variable Interest Entity Interest Sold		$ 1,400,000			1,400,000
Proceeds from Sale of Variable Interest Entity Shares with Agreement to Repurchase		125,000
Financing Receivable, Net, Total		1,275,000			$ 1,275,000
Note Receivable, Quarterly Installment Amount		125,000
Option to Repurchase Variable Interest Entity Shares, Purchase Price		$ 1,400,000
Option to Repurchase Variable Entity Shares at Specified Purchase Price, Period		2 years
Return Obligation, Amount Repaid	$ 250,000
Notes Receivable, Reversal Amount			1,150,000	$ 1,150,000
Equity Method Investment, Reversal of Deferred Gain on Sale			1,400,000
Termination Agreement, Gain (Loss) on Transaction			$ 0