Pension And Other Postretirement Benefit Plans (Recognized In Accumulated Other Comprehensive Income (Loss) On Pretax Basis) (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain), beginning of year	$ 79,299	$ 81,544
Losses (gains) arising during the year	2,313	4,787
Reclassification adjustments during the year	7,567	7,032
Net actuarial loss (gain), end of year	74,045	79,299
Prior service cost (benefit), beginning of year	(15,061)	(17,630)
Prior service cost (benefit) arising during the year	0	111
Reclassification adjustments during the year	2,991	2,458
Prior service cost (benefit), end of year	(12,070)	(15,061)
Total amounts in accumulated other comprehensive loss at end of year, before income taxes	61,975	64,238
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain), beginning of year	(7,234)	(6,402)
Losses (gains) arising during the year	554	(1,263)
Reclassification adjustments during the year	(394)	(431)
Net actuarial loss (gain), end of year	(6,286)	(7,234)
Prior service cost (benefit), beginning of year	(108)	0
Prior service cost (benefit) arising during the year	(4)	(108)
Reclassification adjustments during the year	0	0
Prior service cost (benefit), end of year	(112)	(108)
Total amounts in accumulated other comprehensive loss at end of year, before income taxes	$ (6,398)	$ (7,342)