Employee Benefit Plans (Components of Postretirement Benefit Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning of year	$ 27,503	$ 25,817
Service cost for benefits earned during the period	1,267	1,055	$ 1,108
Interest cost on accumulated post retirement benefit	919	964	943
Net benefit payments and expense	(841)	(93)
Actuarial loss	1,907	(240)
Accumulated postretirement benefit obligation	30,755	27,503	$ 25,817
Liabilities:
Current liabilities	1,334	1,151
Non-currrent liabilities	29,421	26,352
Total post retirement benefit liability recognized in statement of financial position	30,755	27,503
Components included in accumulated other comprehensive income (loss):
Unrecognized net loss	(5,286)	(3,447)
Cumulative net periodic benefit cost (in excess of employer contribution)	$ 25,469	$ 24,056