Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Comprehensive income (loss) (pretax):
Pretax earnings	$ 287,095	$ 246,878	$ 556,103	$ 441,929
Comprehensive income (loss) (tax effect):
Net earnings (Tax)	(103,716)	(90,631)	(201,439)	(161,208)
Comprehensive income (loss) (net of tax):
Net earnings	183,379	156,247	354,664	280,721
Other comprehensive income (loss):
Foreign currency translation (pretax)	$ (13,098)	$ (6,282)	$ (10,565)	$ (3,539)
Foreign currency translation (tax effect)
Foreign currency translation (net of tax)	$ (13,098)	$ (6,282)	$ (10,565)	$ (3,539)
Unrealized gain (loss) on investments (pretax)	(31,625)	20,530	(20,972)	47,142
Unrealized gain (loss) on investments (tax effect)	11,069	(7,186)	7,341	(16,500)
Unrealized gain (loss) on investments (net of tax)	(20,556)	13,344	(13,631)	30,642
Change in fair value of cash flow hedges (pretax)	1,235	4,492	4,605	5,837
Change in fair value of cash flow hedges (tax effect)	(469)	(1,707)	(1,750)	(2,218)
Change in fair value of cash flow hedges (net of tax)	766	2,785	2,855	3,619
Total comprehensive income (loss) (pretax)	243,607	265,618	529,171	491,369
Total comprehensive income (loss) (tax effect)	(93,116)	(99,524)	(195,848)	(179,926)
Total comprehensive income (loss) (net of tax)	$ 150,491	$ 166,094	$ 333,323	$ 311,443