CONDENSED CONSOLIDATED STATEMENTS OF INCOME (unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				6 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Income Statement
Net sales	$ 492,669		$ 383,298		$ 955,461		$ 735,432
Cost of sales	203,806	[1]	189,103	[1]	400,024	[1]	336,440	[1]
Gross profit	288,863		194,195		555,437		398,992
Operating expenses:
Research and development	78,254	[1]	64,082	[1]	151,339	[1]	112,908	[1]
Selling, general and administrative	69,368	[1]	71,767	[1]	135,078	[1]	127,359	[1]
Amortization of acquired intangible assets	23,744		27,858		51,421		31,904
Special (income) charges	(11)		22,394		1,690		22,394
Total operating expenses	171,355		186,101		339,528		294,565
Operating income	117,508		8,094		215,909		104,427
Losses on equity method investments	(101)		(32)		(361)		(153)
Other income (expense):
Interest income	4,010		3,744		7,935		8,076
Interest expense	(12,354)		(10,758)		(24,210)		(19,906)
Other income, net	2,143		1,071		2,269		539
Income before income taxes	111,206		2,119		201,542		92,983
Income tax provision	11,400		23,303		23,157		35,457
Net income (loss)	99,806		(21,184)		178,385		57,526
Basic net income (loss) per common share	$ 0.50		$ (0.11)		$ 0.90		$ 0.30
Diluted net income (loss) per common share	$ 0.46		$ (0.11)		$ 0.83		$ 0.28
Dividends declared per common share	$ 0.3540		$ 0.3510		$ 0.7075		$ 0.7010
Basic common shares outstanding	197,825		194,060		197,388		193,756
Diluted common shares outstanding	216,475		194,060		214,371		204,627
Allocated Share-based Compensation Expense	$ 13,411		$ 17,134		$ 24,665		$ 25,798

[1] Includes share-based compensation expense as follows:Cost of sales 1,864 2,614 3,833 3,924 Research and development 6,931 6,358 12,621 10,390 Selling, general and administrative 6,205 11,581 11,202 16,225