Accumulated Other Comprehensive Income (loss) (Table Text Block)	3 Months Ended
	Jun. 30, 2023
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 Loss     (Unaudited)     (In thousands) Balance as of March 31, 2023 $ (56,539) $   (232,740) $   4,007 $   (351) $   (285,623) Foreign currency translation   469   –   –   –   469 Unrealized net gains on investments   –   20,344   –   –   20,344 Change in fair value of cash flow hedges   –   –   3,842   –   3,842 Amounts reclassified into earnings on hedging activities   –   –   (868)   –   (868) Other comprehensive income (loss)   469   20,344   2,974   –   23,787 Balance as of June 30, 2023$( 56,070 )$ ( 212,396 )$  6,981 $ ( 351 )$  (261,836)