Note 9 - Basic and Diluted Earnings Per Common Share - Reconciliation of Net Income and Number of Shares Used in Computations of Basic and Diluted EPS (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income	$ 8,107,000	$ 437,000	$ 19,668,000	$ 2,665,000
Shares (denominator):
Basic weighted average common shares outstanding (in shares)	13,588,554	13,056,173	13,431,210	13,209,598
Add: dilutive effect of common stock options (in shares)	444,473	19,519	546,354	28,428
Diluted weighted average common shares outstanding (in shares)	14,033,027	13,075,692	13,977,564	13,238,026
Earnings per common share:
Basic (in dollars per share)	$ 0.60	$ 0.03	$ 1.46	$ 0.20
Diluted (in dollars per share)	$ 0.58	$ 0.03	$ 1.41	$ 0.20