Note 15 - Fair Values of Financial Instruments - Assets Measured at Fair Value on a Non-recurring Basis (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Fair value assets		$ 0
Fair Value, Measurements, Nonrecurring [Member]
Fair value assets	$ 160,000	$ 0
Total	160,000
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair value assets
Total
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair value assets
Total
Fair Value, Measurements, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair value assets	160,000
Total	$ 160,000