Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 371,446	$ 241,571	$ 1,365,072	$ 706,908
Comprehensive income (loss) (tax effect):
Income tax expense	(89,980)	(58,586)	(328,533)	(169,832)
Comprehensive income (loss) (net of tax):
Net earnings	281,466	182,985	1,036,539	537,076
Other comprehensive income (loss):
Foreign currency translation (pretax)	112	(2,566)	(2,288)	(5,193)
Foreign currency translation (tax effect)	0	0	0	0
Foreign currency translation (net of tax)	112	(2,566)	(2,288)	(5,193)
Unrealized gain (loss) on investments (pretax)	(15,187)	12,074	(55,113)	68,298
Unrealized gain (loss) on investments (tax effect)	3,195	(2,514)	11,476	(13,398)
Unrealized gain (loss) on investments (net of tax)	(11,992)	9,560	(43,637)	54,900
Change in fair value of cash flow hedges (pretax)	235	35	93	(624)
Change in fair value of cash flow hedges (tax effect)	(57)	(9)	(22)	153
Change in fair value of cash flow hedges (net of tax)	178	26	71	(471)
Amounts reclassified into earnings on hedging activities, (pre tax)	1,007	972	2,997	2,680
Amounts reclassified into earnings on hedging activities (tax effect)	(248)	(238)	(736)	(658)
Amounts reclassified into earnings on hedging activities (net of tax)	759	734	2,261	2,022
Total other comprehensive income (loss) (pretax)	(13,833)	10,515	(54,311)	65,161
Total other comprehensive income (loss) (tax effect)	2,890	(2,761)	10,718	(13,903)
Total other comprehensive income (loss), (net of tax)	(10,943)	7,754	(43,593)	51,258
Total comprehensive income (pretax)	357,613	252,086	1,310,761	772,069
Total comprehensive income (tax effect)	(87,090)	(61,347)	(317,815)	(183,735)
Total comprehensive income (loss) (net of tax)	$ 270,523	$ 190,739	$ 992,946	$ 588,334