Equity Incentive Plans, Stock Compensation Expensed (Details) (USD $)	3 Months Ended				6 Months Ended
	Sep. 30, 2011		Sep. 30, 2010		Sep. 30, 2011		Sep. 30, 2010
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	$ 8,258,000		$ 7,811,000		$ 16,114,000		$ 16,100,000
Inventory [Member]
Stock-based compensation expense [Line Items]
Amount of share-based compensation expense capitalized to inventory	1,700,000		1,700,000		3,300,000		3,700,000
Cost of sales [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	1,608,000	[1]	1,743,000	[1]	3,007,000	[1]	3,708,000	[1]
Research and development [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	3,556,000		3,025,000		6,969,000		6,192,000
Selling, general and administrative [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	4,320,000		4,157,000		8,532,000		8,476,000
Pre-tax effect of share based compensation [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	9,484,000		8,925,000		18,508,000		18,376,000
Income tax benefit [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	$ 1,226,000		$ 1,114,000		$ 2,394,000		$ 2,276,000

[1] During the three and six months ended September 30, 2011, $1.7 million and $3.3 million, respectively, of share-based compensation expense was capitalized to inventory and $1.6 million and $3.0 million, respectively, of previously capitalized share-based compensation expenses in inventory was sold. During the three and six months ended September 30, 2010, $1.7 million and $3.7 million, respectively, of share-based compensation expense was capitalized to inventory and $1.7 million and $3.7 million, respectively, of previously capitalized share-based compensation expense in inventory was sold.