Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013	Dec. 31, 2012
Comprehensive income (loss) (pretax):
Net earnings	$ 82,366	$ 59,870	$ 478,262	$ 359,467
Comprehensive income (loss) (tax effect):
Net earnings	(30,145)	(23,024)	(175,082)	(132,632)
Comprehensive income (loss) (net of tax):
Net earnings	52,221	36,846	303,180	226,835
Other comprehensive income (loss):
Foreign currency translation (pretax)	(3,325)	(1,068)	(5,530)	462
Foreign currency translation (tax effect)	0	0	0	0
Foreign currency translation (net of tax)	(3,325)	(1,068)	(5,530)	462
Unrealized net gain (loss) on investments (pretax)	(2,251)	18,368	(43,257)	30,914
Unrealized net gain (loss) on investments (tax effect)	766	(6,574)	15,020	(10,923)
Unrealized net gain (loss) on investments (net of tax)	(1,485)	11,794	(28,237)	19,991
Change in fair value of cash flow hedges (pretax)	4,398	4,248	16,540	4,501
Change in fair value of cash flow hedges (tax effect)	(1,671)	(1,614)	(6,285)	(1,710)
Change in fair value of cash flow hedges (net of tax)	2,727	2,634	10,255	2,791
Total comprehensive income (loss) (pretax)	81,188	81,418	446,015	395,344
Total comprehensive income (loss) (tax effect)	(31,050)	(31,212)	(166,347)	(145,265)
Total comprehensive income (loss) (net of tax)	$ 50,138	$ 50,206	$ 279,668	$ 250,079