Pension And Other Postretirement Benefit Plans (Components Of Company's Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,477	$ 1,452	$ 3,066	$ 2,907
Interest cost	2,710	2,485	5,447	4,966
Expected return on plan assets	(4,190)	(3,694)	(8,406)	(7,388)
Net amortization and deferral	698	902	1,396	1,804
Net periodic benefit cost	695	1,145	1,503	2,289
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	53	58	106	117
Interest cost	331	330	664	670
Expected return on plan assets	(29)	(25)	(56)	(50)
Net amortization and deferral	(153)	(194)	(305)	(388)
Net periodic benefit cost	$ 202	$ 169	$ 409	$ 349