Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 261,008	$ 371,446	$ 1,165,703	$ 1,365,072
Comprehensive income (loss) (tax effect):
Income tax expense	(61,764)	(89,980)	(280,442)	(328,533)
Comprehensive income (loss) (net of tax):
Net earnings	199,244	281,466	885,261	1,036,539
Other comprehensive income (loss):
Foreign currency translation (pretax)	(215)	112	(757)	(2,288)
Foreign currency translation (tax effect)	0	0	0	0
Foreign currency translation (net of tax)	(215)	112	(757)	(2,288)
Unrealized gain (loss) on investments (pretax)	(116,073)	(15,187)	(426,955)	(55,113)
Unrealized gain (loss) on investments (tax effect)	24,523	3,195	90,579	11,476
Unrealized gain (loss) on investments (net of tax)	(91,550)	(11,992)	(336,376)	(43,637)
Change in fair value cash flow hedges (pretax)	153	235	8,659	93
Change in fair value of cash flow hedges (tax effect)	(38)	(57)	(2,127)	(22)
Change in fair value of cash flow hedges, (net of tax)	115	178	6,532	71
Amounts reclassified into earnings on hedging activities, (pre tax)	(455)	1,007	134	2,997
Amounts reclassified into earnings on hedging activities (tax effect)	110	(248)	(33)	(736)
Amounts reclassified into earnings on hedging activities (net of tax)	(345)	759	101	2,261
Total other comprehensive income (loss) (pretax)	(116,590)	(13,833)	(418,919)	(54,311)
Total other comprehensive income (loss) (tax effect)	24,595	2,890	88,419	10,718
Total other comprehensive income (loss), (net of tax)	(91,995)	(10,943)	(330,500)	(43,593)
Total comprehensive income (pretax)	144,418	357,613	746,784	1,310,761
Total comprehensive income (tax effect)	(37,169)	(87,090)	(192,023)	(317,815)
Total comprehensive income (loss) (net of tax)	$ 107,249	$ 270,523	$ 554,761	$ 992,946