Income Taxes - Tax Credit Carryforwards - Deferred Tax Assets (Details) - USD ($) $ in Millions	Mar. 31, 2021	Mar. 31, 2020
Domestic Tax Authority
Deferred Tax Assets
Deferred tax assets related to research and development credits	$ 6.3	$ 9.7
State
Deferred Tax Assets
Deferred tax assets related to research and development credits	$ 7.6	$ 8.4