Note 6 - Fair Value Measurements (Tables)

3 Months Ended

Jun. 30, 2019

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Total Carrying Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
June 30, 2019:
Assets:
Cash equivalents	$	67,222	$	67,222	$	—	$	—
Derivative liabilities:
Warrants	$	1,702	$	—	$	—	$	1,702

	Total Carrying Value		Quoted Prices in Active Markets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
March 31, 2019:
Assets:
Cash equivalents	$	41,839	$	41,839	$	—	$	—
Derivative liabilities:
Warrants	$	4,942	$	—	$	—	$	4,942

Fair Value, Liabilities Measured on Recurring Basis [Table Text Block]

	Warrants
April 1, 2019	$	4,942
Mark to market adjustment		(2,946	)
Warrant exercise		(294	)
Balance at June 30, 2019	$	1,702

	Warrants
April 1, 2018	$	1,217
Mark to market adjustment		464
Balance at June 30, 2018	$	1,681