Note 13 - Common Shares - Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Repurchased and Retired During Period, Shares	101,816
Stock Repurchased and Retired During Period, Value	$ 4,986
Average price per share (in dollars per share)	$ 48.97
Number of shares (in shares)	21,332	19,777	50,454
Aggregate market value of shares (in thousands)	$ 1,510	$ 1,138	$ 2,602
Average price per share (in dollars per share)	$ 70.77	$ 57.56	$ 51.58