Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 246,878	$ 216,848	$ 441,929	$ 395,896
Comprehensive income (loss) (tax effect):
Net earnings	(90,631)	(78,857)	(161,208)	(144,937)
Comprehensive income (loss) (net of tax):
Net earnings	156,247	137,991	280,721	250,959
Other comprehensive income (loss):
Foreign currency translation (pretax)	(6,282)	1,557	(3,539)	(2,205)
Foreign currency translation (tax effect)	0	0	0	0
Foreign currency translation (net of tax)	(6,282)	1,557	(3,539)	(2,205)
Unrealized gain (loss) on investments (pretax)	20,530	(41,095)	47,142	(41,006)
Unrealized gain (loss) on investments (tax effect)	(7,186)	14,322	(16,500)	14,254
Unrealized gain (loss) on investments (net of tax)	13,344	(26,773)	30,642	(26,752)
Change in fair value of cash flow hedges (pretax)	4,492	1,946	5,837	12,142
Change in fair value of cash flow hedges (tax effect)	(1,707)	(740)	(2,218)	(4,614)
Change in fair value of cash flow hedges (net of tax)	2,785	1,206	3,619	7,528
Total comprehensive income (loss) (pretax)	265,618	179,256	491,369	364,827
Total comprehensive income (loss) (tax effect)	(99,524)	(65,275)	(179,926)	(135,297)
Total comprehensive income (loss) (net of tax)	$ 166,094	$ 113,981	$ 311,443	$ 229,530