Note 9 - Stock Options and Stock-based Employee Compensation (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2020

Dec. 31, 2019

Notes Tables

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]

(in thousands, except for weighted-average data)				Weighted- Average Exercise		Weighted- Average Remaining Contractual
Stock Options	Shares			Price		Term (In Yrs)
Outstanding at January 1, 2020		1,772		$	17.61
Forfeited or expired		(7	)		65.17
Outstanding at March 31, 2020		1,765		$	17.40		8.7
Vested and exercisable at March 31, 2020		599		$	26.66		8.7
Vested and expected to vest at March 31, 2020		1,696		$	17.37		8.8

(in thousands, except for weighted-average data) Stock Options	Shares			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (In Yrs)
Outstanding at January 1, 2019		1,472		$	20.19
Granted		382			9.99
Forfeited or expired		(82	)		40.74
Outstanding at December 31, 2019		1,772		$	17.61		9.0
Vested and exercisable at December 31, 2019		521		$	29.34		8.9
Vested and expected to vest at December 31, 2019		1,692		$	17.55		9.0

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

	Three Months Ended March 31,
(in thousands)	2020		2019
Research and development	$	714	$	489
General and administrative		975		1,041
Total	$	1,689	$	1,530

	Year Ended December 31,
(in thousands)	2019		2018
Research and development	$	1,932	$	232
Selling, general and administrative		4,789		723
Total	$	6,721	$	955