Note 5 - Share-based Compensation (Tables)

3 Months Ended

Mar. 31, 2019

Notes Tables

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	Three Month Period Ended
	March 31, 2019
				Weighted  Avg.
				Exercise
	Options			Price
Outstanding at beginning of year		2,043,402		$	1.91
Granted		—		$	N/A
Exercised		(99,697	)	$	1.61
Forfeited		(3,438	)	$	5.69
Expired		—		$	N/A
Outstanding at March 31, 2019		1,940,267		$	1.92
Stock options exercisable at March 31, 2019		1,657,436		$	1.89

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

	Three Month Period Ended
	March 31, 2019
	Number of Restricted Shares			Grant-Date Fair Value
Unvested outstanding at beginning of year		279,919		$	5.00
Granted		146,614		$	17.84
Vested		(64,992	)	$	4.47
Forfeited		(8,418	)	$	6.66
Unvested outstanding at March 31, 2019		353,123		$	10.39

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Month Period Ended
	March 31,
(I n thousands)	2019		2018
Research and development costs	$	80	$	65
Sales and marketing costs		166		69
General and administrative costs		328		191
Cost of product sales		32		48
Total	$	606	$	373