Note 14 - Subsequent Events - Sale of 555 Building - Proforma Balance Sheet (Details) (Parentheticals) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	20,000,000	20,000,000
Common stock, shares issued (in shares)	6,684,281	6,678,698
Common stock, shares outstanding (in shares)	6,684,281	6,678,698
Pro Forma [Member]
Common stock, par value (in dollars per share)	$ 0.01
Common stock, shares authorized (in shares)	20,000,000
Common stock, shares issued (in shares)	6,678,698
Common stock, shares outstanding (in shares)	6,678,698