Pension And Other Postretirement Benefit Plans (Components Of Company's Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,541	$ 1,589
Interest cost	2,454	2,737
Expected return on plan assets	(3,677)	(4,216)
Net amortization and deferral	1,121	698
Net periodic benefit cost	1,439	808
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	48	53
Interest cost	287	333
Expected return on plan assets	(24)	(27)
Net amortization and deferral	(143)	(152)
Net periodic benefit cost	$ 168	$ 207