Accumulated Other Comprehensive Loss (Summary of Accumulated Other Comprehensive Income (Loss) Components, Net of Tax) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2024	Dec. 31, 2023
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2024			$ 223,216
Foreign currency translation	$ 3,929	$ 5,268	3,712	$ 2,888
Unrealized net gain on investments	54,108	32,785	44,663	25,738
Change in fair value of cash flow hedges	4,611	4,352	4,402	2,823
Amount reclassified from AOCI	1,197	1,109	9,375	2,992
Other comprehensive income (loss)	53,593	32,978	35,978	23,019
Balance as of December 31, 2024	187,238		187,238
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2024	53,490	58,919	53,707	56,539
Foreign currency translation	3,929	5,268	3,712	2,888
Other comprehensive income (loss)	3,929	5,268	3,712	2,888
Balance as of December 31, 2024	57,419	53,651	57,419	53,651
Unrealized Net Gain on Investments [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2024	186,328	225,693	176,883	232,740
Unrealized net gain on investments	54,108	32,785	44,663	25,738
Other comprehensive income (loss)	54,108	32,785	44,663	25,738
Balance as of December 31, 2024	132,220	258,478	132,220	258,478
Fair Market Value of Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2024	2,057	9,299	6,330	4,007
Change in fair value of cash flow hedges	4,611	4,352	4,402	2,823
Amount reclassified from AOCI	1,197	1,109	9,375	2,992
Other comprehensive income (loss)	3,414	5,461	4,973	169
Balance as of December 31, 2024	1,357	3,838	1,357	3,838
Postretirement Benefit Obligation Gain [Member]
Accumulated Other Comprehensive Income (Loss) Components, Net of Tax [Roll Forward]
Balance as of March 31, 2024	1,044	351	1,044	351
Balance as of December 31, 2024	1,044	351	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, 2024	240,831	275,664	223,216	285,623
Foreign currency translation	3,929	5,268	3,712	2,888
Unrealized net gain on investments	54,108	32,785	44,663	25,738
Change in fair value of cash flow hedges	4,611	4,352	4,402	2,823
Amount reclassified from AOCI	1,197	1,109	9,375	2,992
Other comprehensive income (loss)	53,593	32,978	35,978	23,019
Balance as of December 31, 2024	$ 187,238	$ 308,642	$ 187,238	$ 308,642