Provision for Taxes (Effective income tax rate reconciliation) (Details)	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Statutory federal income tax rate	21.00%	21.00%	31.55%
Increase (Reduction) in Rate Resulting from [Abstract]
Deferred tax liability revaluation	0.00%	0.00%	(58.25%)
NOL tax rate benefit	(38.62%)	0.00%	0.00%
State taxes, net of federal benefit	0.02%	2.41%	2.33%
Foreign rate differential	0.21%	0.15%	0.00%
Federal tax credits	0.53%	0.15%	0.32%
Transition tax	0.00%	(0.20%)	1.83%
Tax exempt income	(0.17%)	0.00%	0.00%
Dividends received deduction	0.01%	0.01%	0.03%
Phase III Tax	0.00%	0.00%	0.63%
Other	1.19%	(0.86%)	(1.73%)
Actual tax expense of operations	(16.91%)	22.34%	(23.99%)