Note 2 - Summary of Significant Accounting Policies - Operating Lease Assets and Liabilities (Details) - USD ($)		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Operating lease right-of-use asset
Operating lease right-of-use asset, amortization		65,431
Operating lease right-of-use asset		1,503,669
Operating lease liability, amortization		66,164
Operating lease liability	[1]	1,659,211
Accounting Standards Update 2016-02 [Member]
Operating lease right-of-use asset		1,569,100
Operating lease liability		$ 1,725,375

[1] Includes short-term portion of $296,461 and long-term portion of $1,362,750.