FAIR VALUE MEASUREMENTS (Details) - Recurring basis - USD ($) $ in Thousands	Sep. 30, 2015	Mar. 31, 2015
Assets measured at fair value on a recurring basis
Total recurring fair value measurements, net	$ 888,221	$ 811,702
Cash and Cash Equivalents
Assets measured at fair value on a recurring basis
Money market funds	503,466	544,334
Bank-time deposits	31,971	79,852
Short term investments.
Assets measured at fair value on a recurring basis
Bank-time deposits	248,590	87,500
Corporate bonds	104,371	99,429
Prepaid expenses and other
Assets measured at fair value on a recurring basis
Foreign currency forward contracts		587
Accrued Expenses and other current liabilities
Assets measured at fair value on a recurring basis
Foreign currency forward contracts	(177)
Quoted prices in active markets for identical assets (level 1)
Assets measured at fair value on a recurring basis
Total recurring fair value measurements, net	784,027	711,686
Quoted prices in active markets for identical assets (level 1) | Cash and Cash Equivalents
Assets measured at fair value on a recurring basis
Money market funds	503,466	544,334
Bank-time deposits	31,971	79,852
Quoted prices in active markets for identical assets (level 1) | Short term investments.
Assets measured at fair value on a recurring basis
Bank-time deposits	248,590	87,500
Significant other observable inputs (level 2)
Assets measured at fair value on a recurring basis
Total recurring fair value measurements, net	104,194	100,016
Significant other observable inputs (level 2) | Short term investments.
Assets measured at fair value on a recurring basis
Corporate bonds	104,371	99,429
Significant other observable inputs (level 2) | Prepaid expenses and other
Assets measured at fair value on a recurring basis
Foreign currency forward contracts		$ 587
Significant other observable inputs (level 2) | Accrued Expenses and other current liabilities
Assets measured at fair value on a recurring basis
Foreign currency forward contracts	$ (177)