Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Comprehensive income (loss) (pretax):
Pretax earnings	$ 197,358	$ 278,991	$ 396,044	$ 512,122
Comprehensive income (loss) (tax effect):
Net earnings (Tax)	(72,719)	(102,516)	(145,198)	(188,474)
Comprehensive income (loss) (net of tax):
Net earnings	124,639	176,475	250,846	323,648
Other comprehensive income (loss):
Foreign currency translation (pretax)	12,767	(1,704)	21,034	(1,982)
Foreign currency translation (tax effect)
Foreign currency translation (net of tax)	12,767	(1,704)	21,034	(1,982)
Unrealized gain (loss) on investments (pretax)	15,473	30,790	26,104	60,618
Unrealized gain (loss) on investments (tax effect)	(5,416)	(10,777)	(9,136)	(21,217)
Unrealized gain (loss) on investments (net of tax)	10,057	20,013	16,968	39,401
Change in fair value of cash flow hedges (pretax)	1,194	3,105	2,744	5,186
Change in fair value of cash flow hedges (tax effect)	(454)	(1,179)	(1,044)	(1,970)
Change in fair value of cash flow hedges (net of tax)	740	1,926	1,700	3,216
Total comprehensive income (loss) (pretax)	226,792	311,182	445,926	575,944
Total comprehensive income (loss) (tax effect)	(78,589)	(114,472)	(155,378)	(211,661)
Total comprehensive income (loss) (net of tax)	$ 148,203	$ 196,710	$ 290,548	$ 364,283