Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 169,197	$ 198,686
Comprehensive income (loss) (tax effect):
Net earnings	(41,348)	(72,479)
Comprehensive income (loss) (net of tax):
Net earnings	127,849	126,207
Other comprehensive income (loss):
Foreign currency translation (pretax)	(2,093)	8,267
Foreign currency translation (tax effect)
Foreign currency translation (net of tax)	(2,093)	8,267
Unrealized gain (loss) on investments (pretax)	(50,218)	10,631
Unrealized gain (loss) on investments (tax effect)	10,546	(3,720)
Unrealized gain (loss) on investments (net of tax)	(39,672)	6,911
Change in fair value of cash flow hedges (pretax)	560	1,550
Change in fair value of cash flow hedges (tax effect)	(138)	(590)
Change in fair value of cash flow hedges (net of tax)	422	960
Total comprehensive income (loss) (pretax)	117,446	219,134
Total comprehensive income (loss) (tax effect)	(30,940)	(76,789)
Total comprehensive income (loss) (net of tax)	$ 86,506	$ 142,345