CONSOLIDATED STATEMENTS OF INCOME (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2012		Mar. 31, 2011		Mar. 31, 2010
Income Statement
Net sales	$ 1,383,176,000		$ 1,487,205,000		$ 947,729,000
Cost of sales	590,782,000	[1]	612,769,000	[1]	413,487,000	[1]
Gross profit	792,394,000		874,436,000		534,242,000
Operating expenses:
Research and development	182,650,000	[1]	170,607,000	[1]	120,823,000	[1]
Selling, general and administrative	212,391,000	[1]	227,781,000	[1]	167,222,000	[1]
Special charges, net	837,000		1,865,000		1,238,000
Total operating expenses	395,878,000		400,253,000		289,283,000
Operating income	396,516,000		474,183,000		244,959,000
(Losses) gains on equity method investments	(195,000)		157,000		0
Other income (expense):
Interest income	17,992,000		16,002,000		15,325,000
Interest expense	(34,266,000)		(31,521,000)		(31,150,000)
Other (expense) income, net	(352,000)		1,877,000		8,679,000
Income from continuing operations before income taxes	379,695,000		460,698,000		237,813,000
Income tax provision	42,990,000		31,531,000		20,808,000
Net income from continuing operations	336,705,000		429,167,000		217,005,000
Discontinued operations:
Loss from discontinued operations before income taxes	0		(11,126,000)		0
Income tax benefit	0		(909,000)		0
Net loss from discontinued operations	0		(10,217,000)		0
Net income	$ 336,705,000		$ 418,950,000		$ 217,005,000
Basic net income per common share - continuing operations	$ 1.76		$ 2.29		$ 1.18
Basic net loss per common share - discontinued operations	$ 0.00		$ (0.05)		$ 0.00
Basic net income per common share	$ 1.76		$ 2.24		$ 1.18
Diluted net income per common share - continuing operations	$ 1.65		$ 2.20		$ 1.16
Diluted net loss per common share - discontinued operations	$ 0.00		$ (0.05)		$ 0.00
Diluted net income per common share	$ 1.65		$ 2.15		$ 1.16
Dividends declared per common share	$ 1.390		$ 1.374		$ 1.359
Basic common shares outstanding	191,283		187,066		183,642
Diluted common shares outstanding	203,519		194,715		187,339

[1] Includes share-based compensation expense as follows:Cost of sales 5,648 6,825 7,054Research and development 14,719 12,874 12,194Selling, general and administrative 17,922 17,113 17,530