Note 5 - Common Shares and Earnings Per Share - Reconciliation of Company's Common Shares (Details)	6 Months Ended
	Jun. 30, 2019 shares
Common Shares Outstanding, beginning balance (in shares)	39,664,884
Vesting of Restricted Stock Units (in shares)	26,750
Restricted Stock Issued to Directors (in shares)	15,700
Directors Deferred Compensation (in shares)	594
Shares Withheld for Individual Income Tax Requirements (in shares)	(55,224)
Common Shares Outstanding, ending balance (in shares)	39,754,902
Performance Awards 2016 [Member]
Executive Stock Performance Awards (2016 shares earned) (in shares)	102,198