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, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,343	$ 1,469	$ 4,063	$ 4,431
Interest cost	2,453	2,345	7,389	7,038
Expected return on plan assets	(3,584)	(3,574)	(10,762)	(10,727)
Net amortization and deferral	843	1,201	2,519	3,599
Net periodic benefit cost	1,055	1,441	3,209	4,341
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	73	106	220	320
Interest cost	378	387	1,136	1,186
Expected return on plan assets	(11)	(15)	(33)	(45)
Net amortization and deferral	(100)	(44)	(300)	(132)
Net periodic benefit cost	$ 340	$ 434	$ 1,023	$ 1,329