Employee Benefit Plans (Components of net periodic benefit costs post retirement benefits) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Postemployment Benefits [Abstract]
Service cost for benefits earned during the period	$ 268	$ 257	$ 536	$ 513
Interest cost on accumulated postretirement benefit	217	203	434	407
Other components	15	22	30	44
Net periodic postretirement benefit cost	$ 500	$ 482	$ 1,000	$ 964