Pension And Other Postretirement Benefit Plans (Components Of Company's Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2022
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 5,214	$ 6,172	$ 6,674
Interest cost	11,566	9,670	8,754
Expected return on plan assets	(15,504)	(13,630)	(13,562)
Net amortization and deferral	(659)	2,038	(1,679)
Net periodic benefit cost	1,935	4,250	3,545
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	239	115	170
Interest cost	1,049	944	950
Expected return on plan assets	(63)	(76)	(86)
Net amortization and deferral	791	737	422
Net periodic benefit cost	$ 434	$ 246	$ 612