Pension And Other Postretirement Benefit Plans (Components Of Company's Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,311	$ 1,361
Interest cost	2,434	2,469
Expected return on plan assets	(3,717)	(3,589)
Net amortization and deferral	815	838
Net periodic benefit cost	843	1,079
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	64	73
Interest cost	383	375
Expected return on plan assets	(22)	(11)
Net amortization and deferral	(71)	(100)
Net periodic benefit cost	$ 354	$ 337