Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 174,714	$ 169,197
Comprehensive income (loss) (net of tax):
Net earnings	132,422	127,849
Other comprehensive income (loss):
Foreign currency translation (pretax)	2,982	(2,093)
Foreign currency translation (tax effect)
Foreign currency translation (net of tax)	2,982	(2,093)
Unrealized gain (loss) on investments (pretax)	51,827	(50,218)
Unrealized gain (loss) on investments (tax effect)	(11,039)	10,546
Unrealized gain (loss) on investments (net of tax)	40,788	(39,672)
Change in fair value of cash flow hedges (pretax)	(1,253)	560
Change in fair value of cash flow hedges (tax effect)	308	(138)
Change in fair value of cash flow hedges (net of tax)		422
Total comprehensive income (loss) (pretax)	228,270	117,446
Total comprehensive income (loss) (tax effect)	(53,023)	(30,940)
Total comprehensive income (loss) (net of tax)	$ 175,247	$ 86,506