Employee Benefit Plans (Components of Postretirement Benefit Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning of year	$ 25,817	$ 23,316
Service cost for benefits earned during the period	1,055	1,108	$ 1,073
Interest cost on accumulated post retirement benefit	964	943	869
Net benefit payments and expense	93	979
Actuarial loss	(240)	1,429
Accumulated postretirement benefit obligation	27,503	25,817	$ 23,316
Liabilities:
Current liabilities	1,151	1,037
Non-currrent liabilities	26,352	24,780
Total post retirement benefit liability recognized in statement of financial position	27,503	25,817
Components included in accumulated other comprehensive income (loss):
Unrecognized net loss	(3,447)	(3,890)
Cumulative net periodic benefit cost (in excess of employer contribution)	$ 24,056	$ 21,927