Pension And Other Postretirement Benefit Plans (Components Of Company's Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,359	$ 1,479	$ 2,720	$ 2,962
Interest cost	2,467	2,347	4,936	4,693
Expected return on plan assets	(3,589)	(3,577)	(7,178)	(7,153)
Net amortization and deferral	838	1,199	1,676	2,398
Net periodic benefit cost	1,075	1,448	2,154	2,900
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	74	106	147	214
Interest cost	383	392	758	799
Expected return on plan assets	(11)	(15)	(22)	(30)
Net amortization and deferral	(100)	(44)	(200)	(88)
Net periodic benefit cost	$ 346	$ 439	$ 683	$ 895