Employee Benefit Plans (Components of net periodic post retirement benefit cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2019
Postemployment Benefits [Abstract]
Service cost for benefits earned during the period	$ 1,267	$ 1,055	$ 1,108
Interest cost on accumulated postretirement benefit	919	964	943
Other components	68	90	70
Total other components of net periodic benefit costs	987	1,054	1,013
Net periodic postretirement benefit cost	$ 2,254	$ 2,109	$ 2,121