Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 40,329	$ 103,022	$ 420,397	$ 487,879
Comprehensive income (loss) (net of tax):
Net earnings	30,932	78,635	319,680	370,026
Other comprehensive income (loss):
Foreign currency translation (pretax)	(692)	(4,101)	2,919	(5,081)
Foreign currency translation (tax effect)	0
Foreign currency translation (net of tax)	(692)	(4,101)	2,919	(5,081)
Unrealized gain (loss) on investments (pretax)	28,568	1,827	133,046	(70,671)
Unrealized gain (loss) on investments (tax effect)	(6,190)	(384)	(28,575)	14,841
Unrealized gain (loss) on investments (net of tax)	22,378		104,471
Change in fair value of cash flow hedges (pretax)	479	(1,001)	(1,555)
Change in fair value of cash flow hedges (tax effect)	(118)	246	382	(172)
Change in fair value of cash flow hedges (net of tax)	361	57		528
Amounts reclassified into earnings on hedging activities, (pre tax)	422	886	(3)	31
Amounts reclassified into earnings on hedging activities (tax effect)	(103)	(218)	1	(8)
Amounts reclassified into earnings on hedging activities, net			(2)	23
Total comprehensive income (loss) (pretax)	69,106	100,633	554,804	412,858
Total comprehensive income (loss) (tax effect)	(15,808)	(24,743)	(128,909)	(103,192)
Total comprehensive income (loss) (net of tax)	$ 53,298	$ 75,890	$ 425,895	$ 309,666