Employee Benefit Plans (Components of net periodic benefit costs post retirement benefits) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Postemployment Benefits [Abstract]
Service cost for benefits earned during the period	$ 292	$ 277	$ 584	$ 554
Other components of net periodic benefit costs:
Interest cost on accumulated postretirement benefit	241	236	482	472
Other components	23	18	45	35
Net periodic postretirement benefit cost	$ 556	$ 531	$ 1,111	$ 1,061