Employee Benefit Plans (Components of net periodic benefit costs post retirement benefits) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Postemployment Benefits [Abstract]
Service cost for benefits earned during the period	$ 316	$ 292	$ 633	$ 584
Other components of net periodic benefit costs:
Interest cost on accumulated postretirement benefit	229	241	459	482
Other components	17	23	34	45
Total other components of net periodic benefit costs	246	264	493	527
Net periodic postretirement benefit cost	$ 562	$ 556	$ 1,126	$ 1,111