Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Less: Treasury Common Stock [Member]	Less: Treasury Preferred Stock [Member]	Nonvoting Common Stock [Member] Common Stock [Member]
Balance, beginning of period at Mar. 31, 2024	$ 7,172,445	$ 10,497	$ 462,548	$ (223,216)	$ 7,600,090	$ 525,653	$ 151,997	$ 176
Cosolidated statement of change in equity
Foreign currency translation	3,712			3,712
Unrealized net gain (loss) on investments, net of tax	44,663			44,663
Change in fair value of cash flow hedges	4,402			4,402
Amounts reclassified into earnings on hedging activities, Net	9,375			9,375
Net Income (Loss)	449,381				449,381
Series N Non-Voting Common Stock dividends paid	(26,471)				(26,471)
Net activity	458,888			35,978	422,910
Balance, end of period at Dec. 31, 2024	7,631,333	10,497	462,548	(187,238)	8,023,000	525,653	151,997	176
Balance, beginning of period at Sep. 30, 2024	7,519,398	10,497	462,548	(240,831)	7,964,658	525,653	151,997	176
Cosolidated statement of change in equity
Foreign currency translation	3,929			3,929
Unrealized net gain (loss) on investments, net of tax	54,108			54,108
Change in fair value of cash flow hedges	4,611			4,611
Amounts reclassified into earnings on hedging activities, Net	1,197			1,197
Net Income (Loss)	67,166				67,166
Series N Non-Voting Common Stock dividends paid	(8,824)				(8,824)
Net activity	111,935			53,593	58,342
Balance, end of period at Dec. 31, 2024	7,631,333	10,497	462,548	(187,238)	8,023,000	525,653	151,997	176
Balance, beginning of period at Mar. 31, 2025	7,498,143	10,497	462,548	(229,314)	7,931,886	525,653	151,997	176
Cosolidated statement of change in equity
Foreign currency translation	2,802			2,802
Unrealized net gain (loss) on investments, net of tax	59,460			59,460
Change in fair value of cash flow hedges	3,980			3,980
Amounts reclassified into earnings on hedging activities, Net	2,942			2,942
Net Income (Loss)	210,913				210,913
Series N Non-Voting Common Stock dividends paid	(26,471)				(26,471)
Net activity	245,666			61,224	184,442
Balance, end of period at Dec. 31, 2025	7,743,809	10,497	462,548	(168,090)	8,116,328	525,653	151,997	176
Balance, beginning of period at Sep. 30, 2025	7,767,887	10,497	462,548	(189,804)	8,162,120	(525,653)	151,997	176
Cosolidated statement of change in equity
Foreign currency translation	1,841			1,841
Unrealized net gain (loss) on investments, net of tax	20,026			20,026
Change in fair value of cash flow hedges	457			457
Amounts reclassified into earnings on hedging activities, Net	610			610
Net Income (Loss)	36,968				36,968
Series N Non-Voting Common Stock dividends paid	(8,824)				8,824
Net activity	24,078			21,714	45,792
Balance, end of period at Dec. 31, 2025	$ 7,743,809	$ 10,497	$ 462,548	$ (168,090)	$ 8,116,328	$ 525,653	$ 151,997	$ 176