Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Comprehensive income (loss) (pretax):
Net earnings	$ 172,209	$ 161,470	$ 299,597	$ 287,200
Comprehensive income (loss) (tax effect):
Net earnings	(62,789)	(60,459)	(109,608)	(107,966)
Comprehensive income (loss) (net of tax):
Net earnings	109,420	101,011	189,989	179,234
Other comprehensive income (loss):
Foreign currency translation (pretax)	3,459	(6,749)	1,530	(5,757)
Foreign currency translation (tax effect)	0	0	0	0
Foreign currency translation (net of tax)	3,459	(6,749)	1,530	(5,757)
Unrealized gain (loss) on investments (pretax)	10,673	(1,373)	12,546	(6,751)
Unrealized gain (loss) on investments (tax effect)	(3,769)	741	(4,349)	2,742
Unrealized gain (loss) on investments (net of tax)	6,904	(632)	8,197	(4,009)
Change in fair value of cash flow hedges (pretax)	768	(12,250)	253	(16,110)
Change in fair value of cash flow hedges (tax effect)	(292)	4,655	(96)	6,122
Change in fair value of cash flow hedges (net of tax)	476	(7,595)	157	(9,988)
Total comprehensive income (loss) (pretax)	187,109	141,098	313,926	258,582
Total comprehensive income (loss) (tax effect)	(66,850)	(55,063)	(114,053)	(99,102)
Total comprehensive income (loss) (net of tax)	$ 120,259	$ 86,035	$ 199,873	$ 159,480