Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 198,686	$ 233,131
Comprehensive income (loss) (tax effect):
Net earnings	(72,479)	(85,958)
Comprehensive income (loss) (net of tax):
Net earnings	126,207	147,173
Other comprehensive income (loss):
Foreign currency translation (pretax)	8,267	(278)
Foreign currency translation (tax effect)
Foreign currency translation (net of tax)	8,267	(278)
Unrealized gain (loss) on investments (pretax)	10,631	29,828
Unrealized gain (loss) on investments (tax effect)	(3,720)	(10,440)
Unrealized gain (loss) on investments (net of tax)	6,911	19,388
Change in fair value of cash flow hedges (pretax)	1,550	2,081
Change in fair value of cash flow hedges (tax effect)	(590)	(791)
Change in fair value of cash flow hedges (net of tax)	960	1,290
Total comprehensive income (loss) (pretax)	219,134	264,762
Total comprehensive income (loss) (tax effect)	(76,789)	(97,189)
Total comprehensive income (loss) (net of tax)	$ 142,345	$ 167,573