Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Comprehensive income (loss) (pretax):
Pretax earnings	$ 102,700	$ 132,495	$ 614,822	$ 688,598
Comprehensive income (loss) (tax effect):
Net earnings (Tax)	(37,472)	(50,726)	(225,946)	(252,165)
Comprehensive income (loss) (net of tax):
Net earnings	65,228	81,769	388,876	436,433
Other comprehensive income (loss):
Foreign currency translation (pretax)	(5,821)	(6,727)	(7,803)	(17,292)
Foreign currency translation (tax effect)
Foreign currency translation (net of tax)	(5,821)	(6,727)	(7,803)	(17,292)
Unrealized gain (loss) on investments (pretax)	4,238	1,025	64,856	(19,947)
Unrealized gain (loss) on investments (tax effect)	(1,483)	(359)	(22,700)	6,982
Unrealized gain (loss) on investments (net of tax)	2,755	666	42,156	(12,965)
Change in fair value of cash flow hedges (pretax)	2,853	4,353	8,039	8,958
Change in fair value of cash flow hedges (tax effect)	(931)	(1,654)	(2,901)	(3,404)
Change in fair value of cash flow hedges (net of tax)	1,922	2,699	5,138	5,554
Total comprehensive income (loss) (pretax)	103,970	131,146	679,914	660,317
Total comprehensive income (loss) (tax effect)	(39,886)	(52,739)	(251,547)	(248,587)
Total comprehensive income (loss) (net of tax)	$ 64,084	$ 78,407	$ 428,367	$ 411,730