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, 2018	Mar. 31, 2017
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain), beginning of year	$ 74,045	$ 79,299
Losses (gains) arising during the year	1,390	2,313
Amortization included in net periodic benefit cost during the year	6,102	7,567
Net actuarial loss (gain), end of year	69,333	74,045
Prior service cost (benefit), beginning of year	(12,070)	(15,061)
Prior service cost (benefit) arising during the year	0	0
Amortization included in net periodic benefit cost during the year	2,367	2,991
Prior service cost (benefit), end of year	(9,703)	(12,070)
Total amounts in accumulated other comprehensive loss at end of year, before income taxes	59,630	61,975
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain), beginning of year	(6,286)	(7,234)
Losses (gains) arising during the year	(1,580)	554
Amortization included in net periodic benefit cost during the year	(619)	(394)
Net actuarial loss (gain), end of year	(7,247)	(6,286)
Prior service cost (benefit), beginning of year	(112)	(108)
Prior service cost (benefit) arising during the year	(867)	(4)
Amortization included in net periodic benefit cost during the year	14	0
Prior service cost (benefit), end of year	(965)	(112)
Total amounts in accumulated other comprehensive loss at end of year, before income taxes	$ (8,212)	$ (6,398)