Accumulated Other Comprehensive Income (loss) (Table Text Block)	9 Months Ended
	Dec. 31, 2019
Table Text Block Supplement [Abstract]
Summary of accumulated other comprehensive income (loss) components, net of tax	Foreign Currency Translation   Unrealized Net Gain 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, 2019 $ (56,612) $ (7,259) $ 107 $ (2,934) $ (66,698) Foreign currency translation   2,919   –   –   –   2,919 Unrealized net gain on investments   –   104,471   –   –   104,471 Change in fair value of cash flow hedges   –   –   (1,173)   –   (1,173) Amounts reclassified into earnings on hedging activities   –   –   (2)   –   (2) Other comprehensive income (loss)   2,919   104,471   (1,175)   –   106,215 Balance as of December 31, 2019 $ (53,693) $ 97,212 $ (1,068) $ (2,934) $ 39,517