Note 9 - Convertible Senior Notes (Tables)

3 Months Ended

Mar. 31, 2019

Notes Tables

Schedule of Long-term Debt Instruments [Table Text Block]

	As of
	March 31, 2019			December 31, 2018
Face amount of convertible senior notes	$	88,280		$	88,280
Discount		(25,967	)		(26,138	)
Net carrying value	$	62,313		$	62,142
Carrying amount of equity component included in paid-in capital	$	108,714		$	108,714
Excess of instruments’ if-converted values over face principal amounts	$	—		$	—