Pension And Other Postretirement Benefit Plans (Components Of Company's Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2020
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 6,674	$ 6,618	$ 5,990
Interest cost	8,754	9,571	10,747
Expected return on plan assets	(13,562)	(14,448)	(16,671)
Settlement cost	0	0	676
Net amortization and deferral	1,679	4,863	3,709
Net periodic benefit cost	3,545	6,604	4,451
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	170	172	199
Interest cost	950	1,141	1,306
Expected return on plan assets	(86)	(96)	(106)
Settlement cost	0	0	0
Net amortization and deferral	(422)	(591)	(647)
Net periodic benefit cost	$ 612	$ 626	$ 752