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, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,653	$ 1,547	$ 3,303	$ 3,088
Interest cost	2,254	2,459	4,513	4,913
Expected return on plan assets	(3,387)	(3,679)	(6,772)	(7,356)
Net amortization and deferral	976	1,120	1,952	2,241
Net periodic benefit cost	1,496	1,447	2,996	2,886
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	47	49	94	97
Interest cost	241	286	480	573
Expected return on plan assets	(22)	(24)	(44)	(48)
Net amortization and deferral	(116)	(142)	(231)	(285)
Net periodic benefit cost	$ 150	$ 169	$ 299	$ 337