Accumulated Other Comprehensive Loss (Summary of Accumulated Other Comprehensive Income (Loss) Components, Net of Tax) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2023	$ 223,216
Foreign currency translation	204	$ 469
Unrealized net gain on investments	5,413	20,344
Change in fair value of cash flow hedges	1,905	3,842
Amount reclassified from AOCI	1,075	868
Other comprehensive income (loss)	8,597	23,787
Balance as of June 30, 2024	231,813
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2023	53,707	56,539
Foreign currency translation	204	469
Other comprehensive income (loss)	204	469
Balance as of June 30, 2024	53,911	56,070
Unrealized Net Gain on Investments [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2023	176,883	232,740
Unrealized net gain on investments	5,413	20,344
Other comprehensive income (loss)	5,413	20,344
Balance as of June 30, 2024	182,296	212,396
Fair Market Value of Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2023	6,330	4,007
Change in fair value of cash flow hedges	1,905	3,842
Amount reclassified from AOCI	1,075	868
Other comprehensive income (loss)	2,980	2,974
Balance as of June 30, 2024	3,350	6,981
Postretirement Benefit Obligation Gain [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2023	1,044	351
Balance as of June 30, 2024	1,044	351
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2023	223,216	285,623
Foreign currency translation	204	469
Unrealized net gain on investments	5,413	20,344
Change in fair value of cash flow hedges	1,905	3,842
Amount reclassified from AOCI	1,075	868
Other comprehensive income (loss)	8,597	23,787
Balance as of June 30, 2024	$ 231,813	$ 261,836