Note 8 - Stockholders' Equity - Dividend Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Dividends per share (in dollars per share)	$ 0.40
Dividends	$ 4,570	$ 2,736
Dividends Declared February 10, 2020 [Member]
Dividends per share (in dollars per share)	$ 0.20
Dividends	$ 2,285
Dividends Declared May 4, 2020 [Member]
Dividends per share (in dollars per share)	$ 0.20
Dividends	$ 2,285