Condensed Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011	Dec. 31, 2010
Comprehensive income (loss) (pretax):
Net earnings	$ 2,129	$ 29,041	$ 289,329	$ 272,019
Comprehensive income (loss) (tax effect):
Net earnings	(1,401)	(10,433)	(109,367)	(101,690)
Comprehensive income (loss) (net of tax):
Net earnings	728	18,608	179,962	170,329
Other comprehensive income (loss):
Foreign currency translation (pretax)	1,578	3,317	(4,179)	1,538
Foreign currency translation (tax effect)	0	0	0	0
Foreign currency translation (net of tax)	1,578	3,317	(4,179)	1,538
Unrealized gain (loss) on investments (pretax)	14,079	14,537	7,328	21,300
Unrealized gain (loss) on investments (tax effect)	(4,901)	(5,149)	(2,159)	(7,398)
Unrealized gain (loss) on investments (net of tax)	9,178	9,388	5,169	13,902
Change in fair value of cash flow hedges (pretax)	2,977	15,862	(13,133)	(3,706)
Change in fair value of cash flow hedges (tax effect)	(1,131)	(6,027)	4,991	1,409
Change in fair value of cash flow hedges (net of tax)	1,846	9,835	(8,142)	(2,297)
Total comprehensive income (loss) (pretax)	20,763	62,757	279,345	291,151
Total comprehensive income (loss) (tax effect)	(7,433)	(21,609)	(106,535)	(107,679)
Total comprehensive income (loss) (net of tax)	$ 13,330	$ 41,148	$ 172,810	$ 183,472