Accumulated Other Comprehensive Income (Table Text Block)	12 Months Ended
	Mar. 31, 2022
Table Text Block [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block]	Foreign Currency Translation   Unrealized Net Gain on Investments   Fair Value of Cash Flow Hedges   Postretirement Benefit Obligation Net Loss   Accumulated Other Comprehensive Income (Loss)           (In thousands) Balance as of March 31, 2019 $ (56,612) $   (7,259) $   107 $   (2,934) $   (66,698) Foreign currency translation   9,377   –   –   –   9,377 Unrealized net gain on investments   –   97,943   –   –   97,943 Change in fair value of cash flow hedges   –   –   (6,301)   –   (6,301) Amounts reclassified into earnings on hedging activities   –   –   (2)   –   (2) Change in post retirement benefit obligations   –   –   –   333   333 Other comprehensive income (loss)   9,377   97,943   (6,303)   333   101,350 Balance as of March 31, 2020 $ (47,235) $   90,684 $   (6,196) $   (2,601) $   34,652 Foreign currency translation   (5,694)   –   –   –   (5,694) Unrealized net gain on investments   –   76,969   –   –   76,969 Change in fair value of cash flow hedges   –   –   (429)   –   (429) Amounts reclassified into earnings on hedging activities   –   –   2,746   –   2,746 Change in post retirement benefit obligations   –   –   –   (1,387)   (1,387) Other comprehensive income (loss)   (5,694)   76,969   2,317   (1,387)   72,205 Balance as of March 31, 2021 $ (52,929) $   167,653 $   (3,879) $   (3,988) $ 106,857 Foreign currency translation   (2,828)   –   –   –   (2,828) Unrealized net loss on investments   –   (62,626)   –   –   (62,626) Change in fair value of cash flow hedges   –   –   457   –   457 Amounts reclassified into earnings on hedging activities   –   –   2,978   –   2,978 Change in post retirement benefit obligations   –   –   –   1,546   1,546 Other comprehensive income (loss)   (2,828)   (62,626)   3,435   1,546   (60,473) Balance as of March 31, 2022$( 55,757 )$  105,027 $ ( 444 )$ ( 2,442 )$  46,384