Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 538,876	$ 351,019	$ 993,626	$ 465,337
Comprehensive income (loss) (tax effect):
Income tax expense	(128,978)	(84,654)	(238,553)	(111,246)
Comprehensive income (loss) (net of tax):
Net earnings	409,898	266,365	755,073	354,091
Other comprehensive income (loss):
Foreign currency translation (pretax)	992	290	(2,400)	(2,627)
Foreign currency translation (tax effect)	0	0	0	0
Foreign currency translation (net of tax)	992	290	(2,400)	(2,627)
Unrealized gain (loss) on investments (pretax)	52,525	115,186	(39,926)	56,224
Unrealized gain (loss) on investments (tax effect)	(11,143)	(24,347)	8,281	(10,884)
Unrealized gain (loss) on investments (net of tax)	41,382	90,839	(31,645)	45,340
Change in fair value of cash flow hedges (pretax)	(74)	46	(142)	(659)
Change in fair value of cash flow hedges (tax effect)	18	(11)	35	162
Change in fair value of cash flow hedges (net of tax)	(56)	35	(107)	(497)
Amounts reclassified into earnings on hedging activities (pre tax)	1,003	961	1,990	1,708
Amounts reclassified into earnings on hedging activities (tax effect)	(246)	(237)	(488)	(420)
Amounts reclassified into earnings on hedging activities (net of tax)	757	724	1,502	1,288
Total other comprehensive income (loss) (pretax)	54,446	116,483	(40,478)	54,646
Total other comprehensive income (loss) (tax effect)	(11,371)	(24,595)	7,828	(11,142)
Total other comprehensive income (loss) (net of tax)	43,075	91,888	(32,650)	43,504
Total comprehensive income (loss) (pretax)	593,322	467,502	953,148	519,983
Total comprehensive income (loss) (tax effect)	(140,349)	(109,249)	(230,725)	(122,388)
Total comprehensive income (loss) (net of tax)	$ 452,973	$ 358,253	$ 722,423	$ 397,595