Pension And Other Postretirement Benefit Plans (Components Of Company's Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,314	$ 1,343	$ 3,943	$ 4,063
Interest cost	2,436	2,453	7,309	7,389
Expected return on plan assets	3,717	3,584	11,151	10,762
Net amortization and deferral	815	843	2,445	2,519
Net periodic benefit cost	848	1,055	2,546	3,209
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	64	73	193	220
Interest cost	381	378	1,150	1,136
Expected return on plan assets	22	11	66	33
Net amortization and deferral	(71)	(100)	(213)	(300)
Net periodic benefit cost	$ 352	$ 340	$ 1,064	$ 1,023