Note 3 - Fair Value Measurements (Tables)

3 Months Ended

12 Months Ended

Sep. 30, 2017

Jun. 30, 2017

Notes Tables

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

			Quoted Prices in		Significant
			Active Markets		Other		Significant
(in millions)			for Identical Assets		Observable Inputs		Unobservable Inputs
September 30 , 2017	Total		(Level 1)		(Level 2)		(Level 3)
Cash equivalents	$	17.0	$	6.3	$	10.7	$	—
Short-term investments available-for-sale		14.5		—		14.5		—
Total	$	31.5	$	6.3	$	25.2	$	—

(in millions) June 30, 2017	Total		Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Cash equivalents	$	10.9	$	5.9	$	5.0	$	—
Short-term investments available-for-sale	20.9			—		20.9		—
Total	$	31.8	$	5.9	$	25.9	$	—

			Quoted Prices in
			Active Markets for		Significant Other		Significant
(in millions)			Identical Assets		Observable Inputs		Unobservable
June 30, 201 7	Total		(Level 1)		(Level 2)		Inputs (Level 3)
Cash equivalents	$	10.9	$	5.9	$	5.0	$	—
Short-term investments available-for-sale	20.9			—		20.9		—
Total	$	31.8	$	5.9	$	25.9	$	—

			Quoted Prices in
			Active Markets for		Significant Other		Significant
(in millions)			Identical Assets		Observable Inputs		Unobservable
June 30, 2016	Total		(Level 1)		(Level 2)		Inputs (Level 3)
Cash equivalents	$	1.5	$	1.5	$	—	$	—
Short-term investments available-for-sale	19.3			10.0		9.3		—
Total	$	20.8	$	11.5	$	9.3	$	—

Unrealized Gain (Loss) on Investments [Table Text Block]

(in millions)			Unrealized		Unrealized
September 30 , 2017	At Cost		Gains		(Losses)		At Fair Value
Money market funds	$	6.3	$	-	$	-	$	6.3
Corporate notes		9.7		-		-		9.7
Commercial paper		15.5		-		-		15.5
Total	$	31.5	$	-	$	-	$	31.5

(in millions)			Unrealized		Unrealized
June 30, 2017	At Cost		Gains		(Losses)		At Fair Value
Money market funds	$	5.9	$	—	$	—	$	5.9
Commercial paper		8.5		—		—		8.5
Corporate notes		17.4		—		—		17.4
Total	$	31.8	$	—	$	—	$	31.8

(in millions)			Unrealized		Unrealized
June 30, 2017	At Cost		Gains		(Losses)		At Fair Value
Money market funds	$	5.9	$	—	$	—	$	5.9
Commercial paper		8.5		—		—		8.5
Corporate notes		17.4		—		—		17.4
Total	$	31.8	$	—	$	—	$	31.8

(in millions)			Unrealized		Unrealized
June 30, 2016	At Cost		Gains		(Losses)		At Fair Value
Money market funds	$	1.5	$	—	$	—	$	1.5
Debt securities of U.S. government agencies		2.0		—		—		2.0
U.S. Treasury securities		7.0		—		—		7.0
Corporate notes		2.9		0.1		—		3.0
Certificates of deposit		7.3		—		—		7.3
Total	$	20.7	$	0.1	$	—	$	20.8