Accumulated Other Comprehensive Income (loss) (Table Text Block)	9 Months Ended
	Dec. 31, 2022
Table Text Block Supplement [Abstract]
Summary of accumulated other comprehensive income (loss) components, net of tax	Foreign Currency Translation   Unrealized Net Gains (Losses) on Investments   Fair Market Value of Cash Flow Hedges   Postretirement Benefit Obligation Net Loss   Accumulated Other Comprehensive Income (Loss)     (Unaudited)     (In thousands) Balance as of March 31, 2022 $ (55,757) $   105,027 $   (444) $   (2,442) $   46,384 Foreign currency translation   (757)   –   –   –   (757) Unrealized net loss on investments   –   (336,376)   –   –   (336,376) Change in fair value of cash flow hedges   –   –   6,532   –   6,532 Amounts reclassified into earnings on hedging activities   –   –   101   –   101 Other comprehensive income (loss)   (757)   (336,376)   6,633   –   (330,500) Balance as of December 31, 2022$( 56,514 )$ ( 231,349 )$  6,189 $ ( 2,442 )$  (284,116)