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, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,547	$ 1,477	$ 3,088	$ 3,066
Interest cost	2,459	2,710	4,913	5,447
Expected return on plan assets	(3,679)	(4,190)	(7,356)	(8,406)
Net amortization and deferral	1,120	698	2,241	1,396
Net periodic benefit cost	1,447	695	2,886	1,503
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	49	53	97	106
Interest cost	286	331	573	664
Expected return on plan assets	(24)	(29)	(48)	(56)
Net amortization and deferral	(142)	(153)	(285)	(305)
Net periodic benefit cost	$ 169	$ 202	$ 337	$ 409