Note 12 - Convertible Senior Notes (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

Convertible Debt [Table Text Block]

	March 31,			December 31,
	2020			2019
Principal	$	80,500		$	80,500
Unamortized debt issuance costs		(3,265	)		(3,459	)
Net carrying amount	$	77,235		$	77,041

Interest Income and Interest Expense Disclosure [Table Text Block]

	Three months ended March 31,
	2020			2019
Contractual interest expense		1,006			233
Amortization of debt issuance costs		208			9
Total interest cost	$	1,214		$	242.00
Effective interest rate		5.1	%		5.1	%