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EMPLOYEE BENEFIT PLANS Defined Contribution Plans (Details) - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Mar. 31, 2017
Retirement Benefits [Abstract]      
Defined Contribution Plan, Employer Matching Contribution, Percent of Match 3.00%    
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay 3.00%    
Defined Contribution Plan, Cost $ 22.2 $ 22.0 $ 21.8