Share-Based Compensation (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense		$ 23,026	$ 15,273	$ 37,138	$ 28,594
Income tax benefit		8,574	1,833	12,106	3,253
Net income effect of share-based compensation		14,452	13,440	25,032	25,341
Inventory [Member]
Stock-based compensation expense [Line Items]
Amount of share-based compensation expense capitalized to inventory		1,800	1,600	3,600	3,300
Cost of Sales [Member]
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense	[1]	2,398	2,640	4,055	4,695
Research and development [Member]
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense		8,670	7,261	15,768	13,570
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense [Line Items]
Allocated Share-based Compensation Expense		$ 11,958	$ 5,372	$ 17,315	$ 10,329

[1] During the three and six months ended September 30, 2015, $1.8 million and $3.6 million, respectively, of share-based compensation expense was capitalized to inventory and $2.4 million and $4.1 million, respectively, of previously capitalized share-based compensation expense in inventory was sold. During the three and six months ended September 30, 2014, $1.6 million and $3.3 million, respectively, of share-based compensation expense was capitalized to inventory and $2.6 million and $4.7 million, respectively, of previously capitalized share-based compensation expense in inventory was sold.