Employee Benefit Plans (Components of Postretirement Benefit Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning of year	$ 23,316	$ 22,247
Service cost for benefits earned during the period	1,108	1,073	$ 1,026
Interest cost on accumulated post retirement benefit	943	869	814
Net benefit payments and expense	(979)	(644)
Actuarial loss	1,429	(229)
Accumulated postretirement benefit obligation	25,817	23,316	$ 22,247
Liabilities:
Current liabilities	1,037	802
Non-currrent liabilities	24,780	22,514
Total post retirement benefit liability recognized in statement of financial position	25,817	23,316
Components included in accumulated other comprehensive income (loss):
Unrecognized net loss	(3,890)	(2,530)
Cumulative net periodic benefit cost (in excess of employer contribution)	$ 21,927	$ 20,786