DEFERRED COMPENSATION (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Mar. 31, 2016
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Bank deposits held	$ 303,116	$ 301,970	$ 244,455	$ 235,266
Other long-term liabilities [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Deferred compensation liability, noncurrent	15,500	13,700
Short-term investments [Member] | Mutual Funds [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Investments	14,200	12,400
Bank Time Deposits [Member] | Cash and Cash Equivalents [Member]
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]
Bank deposits held	$ 800	$ 800