FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Mar. 31, 2018

Fair Value Disclosures [Abstract]

Segregation of all assets measured at fair value on a recurring basis

The table below segregates all assets that are measured at fair value on a recurring basis (which is measured at least annually) into the most appropriate level within the fair value hierarchy based on the inputs used to determine the fair value at the measurement date.

	March 31, 2018			Quoted prices in active markets for identical assets (level 1)		Significant other observable inputs (level 2)			Significant unobservable inputs (level 3)		Balance Sheet Classification
Money market funds	$	516,626		$	516,626	$	—		$	—	Cash and cash equivalents
Bank-time deposits	21			21		—			—		Cash and cash equivalents
Commercial paper	10,796			—		10,796			—		Cash and cash equivalents
Corporate bonds	308,716			—		308,716			—		Short-term investments
US Treasuries	59,725			59,725		—			—		Short-term investments
Commercial paper	25,422			—		25,422			—		Short-term investments
Mutual funds	4,880			—		4,880			—		Short-term investments
Bank-time deposits	216,663			216,663		—			—		Short-term investments
Foreign currency forward contracts	12			—		12			—		Prepaid expenses and other
Foreign currency forward contracts	(43		)	—		(43		)	—		Accrued and other current liabilities
Cross-currency swap	(15,659		)	—		(15,659		)	—		Accrued and other current liabilities
Private equity	1,205			—		—			1,205		Other assets
Total recurring fair value measurements, net	$	1,128,364		$	793,035	$	334,124		$	1,205

	March 31, 2017			Quoted prices in active markets for identical assets (level 1)		Significant other observable inputs (level 2)			Significant unobservable inputs (level 3)			Balance Sheet Classification
Money market funds	$	646,386		$	646,386	$	—		$	—		Cash and cash equivalents
Bank-time deposits	46,605			46,605		—			—			Cash and cash equivalents
Commercial paper	38,268			—		38,268			—			Cash and cash equivalents
Corporate bonds	243,019			—		243,019			—			Short-term investments
Bank-time deposits	175,745			175,745		—			—			Short-term investments
Commercial paper	25,936			—		25,936			—			Short-term investments
Mutual funds	4,232			—		4,232			—			Short-term investments
Foreign currency forward contracts	2			—		2			—			Prepaid expenses and other
Foreign currency forward contracts	(352		)	—		(352		)	—			Accrued and other current liabilities
Private equity	570			—		—			570			Other assets
Contingent consideration	(6,465		)	—		—			(6,465		)	Other long-term liabilities
Total recurring fair value measurements, net	$	1,173,946		$	868,736	$	311,105		$	(5,895	)