Pension And Other Postretirement Benefit Plans (Components Of Company's Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,650	$ 1,541
Interest cost	2,259	2,454
Expected return on plan assets	(3,385)	(3,677)
Net amortization and deferral	976	1,121
Net periodic benefit cost	1,500	1,439
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	47	48
Interest cost	239	287
Expected return on plan assets	(22)	(24)
Net amortization and deferral	(115)	(143)
Net periodic benefit cost	$ 149	$ 168