Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Operating loss carryforwards, expiration dates	Mar. 31, 2029
Accrued penalties and interest	$ 0.0	$ 0.0	$ 0.0
Federal
Operating Loss Carryforwards	157.6
Research Tax Credit Carryforwards	$ 7.2
Research Tax Credit Carryforwards, Expiration Dates	Mar. 31, 2021
State
Operating Loss Carryforwards	$ 27.5
Research Tax Credit Carryforwards	$ 9.1