STOCK-BASED COMPENSATION - COMPENSATION EXPENSE (Details) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Stock-based compensation expense
Stock-based compensation expense	$ 81,879	$ 69,996	$ 65,246
Capitalized stock-based compensation expense	74,717	30,367	17,423
Cost of goods sold
Stock-based compensation expense
Stock-based compensation expense	21,056	15,323	17,121
Selling and marketing
Stock-based compensation expense
Stock-based compensation expense	9,963	9,425	8,798
General and administrative
Stock-based compensation expense
Stock-based compensation expense	42,908	40,322	33,636
Research and development
Stock-based compensation expense
Stock-based compensation expense	$ 7,952	$ 4,926	$ 5,691