CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) (USD $) Share data in Thousands, except Per Share data	3 Months Ended				6 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Income Statement
Net sales	$ 340,602,000		$ 382,271,000		$ 715,109,000		$ 739,396,000
Cost of sales	145,608,000	[1]	157,266,000	[1]	300,367,000	[1]	306,948,000	[1]
Gross profit	194,994,000		225,005,000		414,742,000		432,448,000
Operating expenses:
Research and development	45,383,000	[1]	43,720,000	[1]	90,681,000	[1]	84,250,000	[1]
Selling, general and administrative	51,991,000	[1]	57,584,000	[1]	109,581,000	[1]	114,796,000	[1]
Special charges	0		558,000		0		1,033,000
Total operating expenses	97,374,000		101,862,000		200,262,000		200,079,000
Operating income	97,620,000		123,143,000		214,480,000		232,369,000
Losses on equity method investments	(13,000)		(43,000)		(74,000)		(95,000)
Other income (expense):
Interest income	4,028,000		4,070,000		8,034,000		8,416,000
Interest expense	(8,911,000)		(8,045,000)		(16,926,000)		(15,784,000)
Other, net	(2,454,000)		1,873,000		(1,418,000)		1,372,000
Income from continuing operations before income taxes	90,270,000		120,998,000		204,096,000		226,278,000
Income tax provision	10,983,000		16,250,000		25,516,000		29,653,000
Net income from continuing operations	79,287,000		104,748,000		178,580,000		196,625,000
Discontinued operations:
Loss from discontinued operations before income taxes	0		(1,756,000)		0		(4,055,000)
Income tax benefit	0		(88,000)		0		(76,000)
Net loss from discontinued operations	0		(1,668,000)		0		(3,979,000)
Net income	$ 79,287,000		$ 103,080,000		$ 178,580,000		$ 192,646,000
Basic net income per common share - continuing operations	$ 0.42		$ 0.56		$ 0.94		$ 1.06
Basic net loss per common share - discontinued operations	$ 0.00		$ (0.01)		$ 0.00		$ (0.02)
Basic net income per common share	$ 0.42		$ 0.55		$ 0.94		$ 1.04
Diluted net income per common share - continuing operations	$ 0.40		$ 0.55		$ 0.88		$ 1.03
Diluted net loss per common share - discontinued operations	$ 0.00		$ (0.01)		$ 0.00		$ (0.02)
Diluted net income per common share	$ 0.40		$ 0.54		$ 0.88		$ 1.01
Dividends declared per common share	$ 0.347		$ 0.343		$ 0.693		$ 0.685
Basic common shares outstanding	190,809		186,303		190,461		185,922
Diluted common shares outstanding	200,199		190,704		202,383		190,388

[1] Includes share-based compensation expense as follows: Cost of sales: $1,608, $1,743, $3,007 and $3,708; Research and development: $3,556, $3,025, $6,969 and $6,192; and Selling, general and administrative: $4,320, $4,157, $8,532 and $8,476 for current periods and prior periods, respectively.