Employee Benefit Plans (Components of net periodic post retirement benefit cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Postemployment Benefits [Abstract]
Service cost for benefits earned during the period	$ 1,055	$ 1,108	$ 1,073
Interest cost on accumulated postretirement benefit	964	943	869
Other components	90	70	58
Net periodic postretirement benefit cost	$ 2,109	$ 2,121	$ 2,000