Note 7 - Share-based Compensation - Stock Option Transactions (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2020	Dec. 31, 2019
Outstanding, options (in shares)		701,131
Outstanding, weighted average exercise price (in dollars per share)		$ 16.82
Outstanding, weighted average remaining life (Year)		3 years 135 days	2 years 346 days
Outstanding, aggregate intrinsic value		$ 217	$ 714
Granted (in shares)	[1]	163,545
Granted, weighted average exercise price (in dollars per share)	[1]	$ 10.97
Exercised (in shares)
Exercised, weighted average exercise price (in dollars per share)
Lapsed or cancelled (in shares)		(97,172)
Lapsed or cancelled, weighted average exercise price (in dollars per share)		$ 18
Outstanding, options (in shares)		767,504	701,131
Outstanding, weighted average exercise price (in dollars per share)		$ 15.42	$ 16.82
Exercisable, options (in shares)		421,123
Exercisable, weighted average exercise price, options (in dollars per share)		$ 16.12
Exercisable, weighted average remaining life, options (Year)		2 years 164 days
Exercisable, aggregate intrinsic value, options		$ 217

[1] The weighted average grant date fair value of stock options granted was $2.14 per share.