CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2011		Dec. 31, 2010
Income Statement
Net sales	$ 329,156,000		$ 367,824,000		$ 1,044,265,000		$ 1,107,220,000
Cost of sales	145,377,000	[1]	151,427,000	[1]	445,744,000	[1]	458,375,000	[1]
Gross profit	183,779,000		216,397,000		598,521,000		648,845,000
Operating expenses:
Research and development	44,256,000	[1]	42,198,000	[1]	134,937,000	[1]	126,448,000	[1]
Selling, general and administrative	52,056,000	[1]	56,100,000	[1]	161,637,000	[1]	170,896,000	[1]
Special (income) charges	(660,000)		646,000		(660,000)		1,679,000
Total operating expenses	95,652,000		98,944,000		295,914,000		299,023,000
Operating income	88,127,000		117,453,000		302,607,000		349,822,000
Gains (losses) on equity method investments	14,000		280,000		(60,000)		185,000
Other income (expense):
Interest income	4,374,000		3,955,000		12,408,000		12,371,000
Interest expense	(8,994,000)		(7,672,000)		(25,920,000)		(23,456,000)
Other, net	156,000		375,000		(1,262,000)		1,747,000
Income from continuing operations before income taxes	83,677,000		114,391,000		287,773,000		340,669,000
Income tax provision	6,188,000		12,461,000		31,704,000		42,114,000
Net income from continuing operations	77,489,000		101,930,000		256,069,000		298,555,000
Discontinued operations:
Loss from discontinued operations before income taxes	0		(1,317,000)		0		(5,372,000)
Income tax benefit	0		(163,000)		0		(239,000)
Net loss from discontinued operations	0		(1,154,000)		0		(5,133,000)
Net income	$ 77,489,000		$ 100,776,000		$ 256,069,000		$ 293,422,000
Basic net income per common share - continuing operations	$ 0.40		$ 0.54		$ 1.34		$ 1.60
Basic net loss per common share - discontinued operations	$ 0.00		$ (0.01)		$ 0.00		$ (0.03)
Basic net income per common share	$ 0.40		$ 0.54		$ 1.34		$ 1.57
Diluted net income per common share - continuing operations	$ 0.38		$ 0.52		$ 1.26		$ 1.55
Diluted net loss per common share - discontinued operations	$ 0.00		$ (0.01)		$ 0.00		$ (0.03)
Diluted net income per common share	$ 0.38		$ 0.51		$ 1.26		$ 1.53
Dividends declared per common share	$ 0.348		$ 0.689		$ 1.041		$ 1.374
Basic common shares outstanding	191,640		187,488		190,854		186,444
Diluted common shares outstanding	203,291		196,255		202,686		192,344

[1] Includes share-based compensation expense as follows: Cost of sales: $1,369, $1,708, $4,376 and $5,416; Research and development: $3,851, $3,324, $10,820 and $9,516; and Selling, general and administrative: $4,742, $4,377, $13,274 and $12,853 for current periods and prior periods, respectively.