Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Comprehensive income (loss) (pretax):
Pretax earnings (loss)	$ 269,008	$ 195,051
Comprehensive income (loss) (tax effect):
Net earnings	(97,723)	(70,577)
Comprehensive income (loss) (net of tax):
Net earnings	171,285	124,474
Other comprehensive income (loss):
Foreign currency translation (pretax)	$ 2,533	$ 2,743
Foreign currency translation (tax effect)
Foreign currency translation (net of tax)	$ 2,533	$ 2,743
Unrealized gain (loss) on investments (pretax)	10,653	26,612
Unrealized gain (loss) on investments (tax effect)	(3,728)	(9,314)
Unrealized gain (loss) on investments (net of tax)	6,925	17,298
Change in fair value of cash flow hedges (pretax)	3,370	1,345
Change in fair value of cash flow hedges (tax effect)	(1,281)	(511)
Change in fair value of cash flow hedges (net of tax)	2,089	834
Total comprehensive income (loss) (pretax)	285,564	225,751
Total comprehensive income (loss) (tax effect)	(102,732)	(80,402)
Total comprehensive income (loss) (net of tax)	$ 182,832	$ 145,349