CONSOLIDATED STATEMENTS OF INCOME CONSOLIDATED STATEMENTS OF INCOME (PARENTHETICAL) - USD ($) $ in Thousands		12 Months Ended
		Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Allocated share based compensation expense		$ 71,420	$ 58,596	$ 53,787
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Allocated share based compensation expense	[1]	8,252	9,010	7,340
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Allocated share based compensation expense		32,022	28,164	24,554
Selling General And Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Allocated share based compensation expense		$ 31,146	$ 21,422	$ 21,893

[1] During the year ended March 31, 2016, $7.9 million of share-based compensation expense was capitalized to inventory, and $8.3 million of previously capitalized share-based compensation expense in inventory was sold. During the year ended March 31, 2015, $6.8 million of share-based compensation expense was capitalized to inventory, and $9.0 million of previously capitalized share-based compensation expense in inventory was sold. During the year ended March 31, 2014, $7.4 million of share-based compensation expense was capitalized to inventory, and $7.3 million of previously capitalized share-based compensation expense in inventory was sold.