Equity Incentive Plans, Stock Compensation Expensed (Details) (USD $)	3 Months Ended				9 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2011		Dec. 31, 2010
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	$ 8,701,000		$ 8,243,000		$ 24,815,000		$ 24,343,000
Inventory [Member]
Stock-based compensation expense [Line Items]
Amount of share-based compensation expense capitalized to inventory	1,700,000		1,700,000		4,900,000		5,400,000
Cost of sales [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	1,369,000	[1]	1,708,000	[1]	4,376,000	[1]	5,416,000	[1]
Research and development [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	3,851,000		3,324,000		10,820,000		9,516,000
Selling, general and administrative [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	4,742,000		4,377,000		13,274,000		12,853,000
Pre-tax effect of share based compensation [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	9,962,000		9,409,000		28,470,000		27,785,000
Income tax benefit [Member]
Stock-based compensation expense [Line Items]
Allocated share based compensation expense	$ 1,261,000		$ 1,166,000		$ 3,655,000		$ 3,442,000

[1] During the three and nine months ended December 31, 2011, $1.7 million and $4.9 million, respectively, of share-based compensation expense was capitalized to inventory and $1.4 million and $4.4 million, respectively, of previously capitalized share-based compensation expenses in inventory was sold. During the three and nine months ended December 31, 2010, $1.7 million and $5.4 million, respectively, of share-based compensation expense was capitalized to inventory and $1.7 million and $5.4 million, respectively, of previously capitalized share-based compensation expense in inventory was sold.