Share-Based Compensation (Details) (USD $)	3 Months Ended				9 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2013		Dec. 31, 2012
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense	$ 12,209,000		$ 11,365,000		$ 36,874,000		$ 37,163,000
Inventory [Member]
Stock-based compensation expense [Line Items]
Amount of share-based compensation expense capitalized to inventory	1,900,000		1,800,000		5,700,000		5,300,000
Cost of Sales [Member]
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense	1,841,000	[1]	1,834,000	[1]	5,674,000	[1]	5,758,000	[1]
Research and development [Member]
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense	6,141,000		6,172,000		18,762,000		16,562,000
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense	5,737,000		6,114,000		16,939,000		22,339,000
Pre-tax effect of share based compensation [Member]
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense	13,719,000		14,120,000		41,375,000		44,659,000
Income tax benefit [Member]
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense	$ 1,510,000		$ 2,755,000		$ 4,501,000		$ 7,496,000

[1] During the three and nine months ended December 31, 2013, $1.9 million and $5.7 million, respectively, of share-based compensation expense was capitalized to inventory and $1.8 million and $5.7 million, respectively, of previously capitalized share-based compensation expenses in inventory was sold. During the three and nine months ended December 31, 2012, $1.8 million and $5.3 million, respectively, of share-based compensation expense was capitalized to inventory and $1.8 million and $5.8 million, respectively, of previously capitalized share-based compensation expense in inventory was sold.