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, 2019	Mar. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain), beginning of year	$ 69,333	$ 74,045
Losses (gains) arising during the year	17,884	1,390
Amortization included in net periodic benefit cost during the year	5,715	6,102
Net actuarial loss (gain), end of year	81,502	69,333
Prior service cost (benefit), beginning of year	(9,703)	(12,070)
Prior service cost (benefit) arising during the year	0	0
Amortization included in net periodic benefit cost during the year	2,224	2,367
Prior service cost (benefit), end of year	(7,479)	(9,703)
Total amounts in accumulated other comprehensive loss at end of year, before income taxes	74,023	59,630
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain), beginning of year	(7,247)	(6,286)
Losses (gains) arising during the year	513	(1,580)
Amortization included in net periodic benefit cost during the year	(533)	(619)
Net actuarial loss (gain), end of year	(6,201)	(7,247)
Prior service cost (benefit), beginning of year	(965)	(112)
Prior service cost (benefit) arising during the year	0	(867)
Amortization included in net periodic benefit cost during the year	199	14
Prior service cost (benefit), end of year	(766)	(965)
Total amounts in accumulated other comprehensive loss at end of year, before income taxes	$ (6,967)	$ (8,212)