Commitments and Contingencies Restructuring Costs (Details) $ in Millions	6 Months Ended
	Oct. 31, 2015 USD ($)
Restructuring Cost and Reserve [Line Items]
Severance Costs	$ 0.2
One-time Termination Benefits [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost Remaining	0.3
Employee Relocation [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost	$ 0.1