CONSOLIDATED STATEMENTS OF INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Mar. 31, 2012
Income Statement
Net sales	$ 1,931,217		$ 1,581,623		$ 1,383,176
Cost of sales (1)	802,474	[1]	743,164	[1]	583,882	[1]
Gross profit	1,128,743		838,459		799,294
Operating expenses:
Research and development (1)	305,043	[1]	254,723	[1]	182,650	[1]
Selling, general and administrative (1)	267,278	[1]	261,471	[1]	208,328	[1]
Amortization of acquired intangible assets	94,534		111,537		10,963
Special charges	3,024		32,175		837
Total operating expenses	669,879		659,906		402,778
Operating income	458,864		178,553		396,516
Losses on equity method investments	(177)		(617)		(195)
Other income (expense):
Interest income	16,485		15,560		17,992
Interest expense	(48,716)		(40,915)		(34,266)
Other income (expense), net	5,898		(404)		(352)
Income before income taxes	432,354		152,177		379,695
Income tax provision	37,073		24,788		42,990
Net income	$ 395,281		$ 127,389		$ 336,705
Basic net income per common share	$ 1.99		$ 0.65		$ 1.76
Diluted net income per common share	$ 1.82		$ 0.62		$ 1.65
Dividends declared per common share	$ 1.417		$ 1.406		$ 1.390
Basic common shares outstanding	198,291		194,595		191,283
Diluted common shares outstanding	217,630		205,776		203,519

[1] Includes share-based compensation expense as follows:Cost of sales 7,340 8,234 5,648Research and development 24,554 22,178 14,719Selling, general and administrative 21,893 27,603 17,922