EMPLOYEE BENEFIT PLANS Schedule of Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	$ 508,375	$ 455,539	$ 454,946
Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	26,373	70,650
Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	482,002	384,889
Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	26,373	70,650
Cash and cash equivalents | Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	26,373	70,650
Cash and cash equivalents | Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Cash and cash equivalents | Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Cash plus
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	105,070
Cash plus | Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0
Cash plus | Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	105,070
Cash plus | Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0
Equity investments - U.K.
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1,683	47,392
Equity investments - U.K. | Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Equity investments - U.K. | Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1,683	47,392
Equity investments - U.K. | Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Equity investments - Non-U.K.
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	151,923	185,567
Equity investments - Non-U.K. | Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Equity investments - Non-U.K. | Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	151,923	185,567
Equity investments - Non-U.K. | Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Property
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	15,852
Property | Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0
Property | Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	15,852
Property | Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0
Diversified growth (absolute return) funds
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1,824
Diversified growth (absolute return) funds | Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0
Diversified growth (absolute return) funds | Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	1,824
Diversified growth (absolute return) funds | Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0
Government debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	124,428	80,654
Government debt securities | Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Government debt securities | Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	124,428	80,654
Government debt securities | Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Corporate debt securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	81,222	71,276
Corporate debt securities | Fair value, inputs, Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	0	0
Corporate debt securities | Fair value, inputs, Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	81,222	71,276
Corporate debt securities | Fair value, inputs, Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value of assets	$ 0	$ 0