Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 233,131	$ 269,008
Comprehensive income (loss) (tax effect):
Net earnings	(85,958)	(97,723)
Comprehensive income (loss) (net of tax):
Net earnings	147,173	171,285
Other comprehensive income (loss):
Foreign currency translation (pretax)	(278)	2,533
Foreign currency translation (tax effect)
Foreign currency translation (net of tax)	(278)	2,533
Unrealized gain (loss) on investments (pretax)	29,828	10,653
Unrealized gain (loss) on investments (tax effect)	(10,440)	(3,728)
Unrealized gain (loss) on investments (net of tax)	19,388	6,925
Change in fair value of cash flow hedges (pretax)	2,081	3,370
Change in fair value of cash flow hedges (tax effect)	(791)	(1,281)
Change in fair value of cash flow hedges (net of tax)	1,290	2,089
Total comprehensive income (loss) (pretax)	264,762	285,564
Total comprehensive income (loss) (tax effect)	(97,189)	(102,732)
Total comprehensive income (loss) (net of tax)	$ 167,573	$ 182,832