FAIR VALUE MEASUREMENT OF ASSETS AND LIABILITIES - Assets and Liabilities Measured at Fair Value (Details) - Recurring Basis - USD ($) $ in Thousands	Dec. 31, 2016	Mar. 31, 2016
Money market funds and time deposits
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	$ 751,027	$ 1,074,132
Deferred purchase price receivable (Note 10)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	668,918	501,097
Foreign exchange contracts (Note 8)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	27,935	22,648
Total Liabilities	(22,928)	(21,091)
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	57,208	49,784
Contingent consideration in connection with business acquisitions
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Liabilities	(28,062)	(73,423)
Level 1 | Money market funds and time deposits
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	0	0
Level 1 | Deferred purchase price receivable (Note 10)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	0	0
Level 1 | Foreign exchange contracts (Note 8)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	0	0
Total Liabilities	0	0
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	6,686	9,228
Level 1 | Contingent consideration in connection with business acquisitions
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Liabilities	0	0
Level 2 | Money market funds and time deposits
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	751,027	1,074,132
Level 2 | Deferred purchase price receivable (Note 10)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	0	0
Level 2 | Foreign exchange contracts (Note 8)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	27,935	22,648
Total Liabilities	(22,928)	(21,091)
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	50,522	40,556
Level 2 | Contingent consideration in connection with business acquisitions
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Liabilities	0	0
Level 3 | Money market funds and time deposits
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	0	0
Level 3 | Deferred purchase price receivable (Note 10)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	668,918	501,097
Level 3 | Foreign exchange contracts (Note 8)
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Assets	0	0
Total Liabilities	0	0
Level 3 | 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	0	0
Level 3 | Contingent consideration in connection with business acquisitions
Financial Instruments Measured at Fair Value on a Recurring Basis and Nonrecurring Basis
Total Liabilities	$ (28,062)	$ (73,423)