FAIR VALUE MEASUREMENT OF ASSETS AND LIABILITIES - Fair Value Hierarchy (Details) - USD ($)	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2017
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Transfers out of Level 2 and into Level 1 related to assets and liabilities measured on a recurring and nonrecurring basis	$ 0	$ 0
Impairment charges for assets no longer in use and held for sale	0
Recurring Basis | Level 1 | Deferred compensation plan assets: Mutual funds, money market accounts and equity securities
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	9,228,000	7,062,000
Recurring Basis | Level 2 | Money market funds and time deposits (Note 2)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	1,074,132,000	1,066,841,000
Recurring Basis | Level 2 | Foreign exchange forward contracts (Note 8)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	22,648,000	22,022,000
Total Liabilities	(21,091,000)	(11,742,000)
Recurring Basis | Level 2 | Deferred compensation plan assets: Mutual funds, money market accounts and equity securities
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	40,556,000	52,680,000
Recurring Basis | Level 3 | Deferred purchase price receivable (Note 10)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	501,097,000	506,522,000
Recurring Basis | Level 3 | Contingent consideration in connection with business acquisitions
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Liabilities	(73,423,000)	(22,426,000)
Total | Recurring Basis | Money market funds and time deposits (Note 2)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	1,074,132,000	1,066,841,000
Total | Recurring Basis | Deferred purchase price receivable (Note 10)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	501,097,000	506,522,000
Total | Recurring Basis | Foreign exchange forward contracts (Note 8)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	22,648,000	22,022,000
Total Liabilities	(21,091,000)	(11,742,000)
Total | Recurring Basis | Deferred compensation plan assets: Mutual funds, money market accounts and equity securities
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	49,784,000	59,742,000
Total | Recurring Basis | Contingent consideration in connection with business acquisitions
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Liabilities	$ (73,423,000)	$ (22,426,000)