Income Taxes - Federal and State tax credit carryforwards (Details) - USD ($)	Mar. 31, 2020	Mar. 31, 2019
Deferred tax assets, tax credit carryforwards
Federal research credits	$ 3,520,000	$ 2,347,000
Valuation allowance on deferred tax assets	14,163,000	$ 12,250,000
Federal
Deferred tax assets, tax credit carryforwards
Alternative minimum tax credit carryforwards	551,000
Federal research credits	2,500,000
Net operating loss carryforwards	10,700,000
Federal | 2022
Deferred tax assets, tax credit carryforwards
Net operating loss carryforwards	7,300,000
State
Deferred tax assets, tax credit carryforwards
Tax credit carryforwards	1,300,000
State | 2031
Deferred tax assets, tax credit carryforwards
Net operating loss carryforwards	$ 8,700,000