Employee Benefit Plans (Components of net periodic benefit costs post retirement benefits) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Postemployment Benefits [Abstract]
Service cost for benefits earned during the period	$ 277	$ 269	$ 831	$ 805
Other components of net periodic benefit cost:
Interest cost on accumulated postretirement benefit	235	218	707	652
Other components	18	13	53	43
Total other components of net periodic benefit costs	253	231	760	695
Net periodic postretirement benefit cost	$ 530	$ 500	$ 1,591	$ 1,500