Employee Benefit Plans (Components of net periodic benefit costs post retirement benefits) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Postemployment Benefits [Abstract]
Service cost for benefits earned during the period	$ 277	$ 268
Other components of net periodic benefit costs:
Interest cost on accumulated postretirement benefit	236	217
Other components	17	15
Total other components of net periodic benefit costs	253	232
Net periodic postretirement benefit cost	$ 530	$ 500