EMPLOYEE BENEFIT PLANS (Details) $ / shares in Units, $ in Thousands, £ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 GBP (£)	Mar. 31, 2015 USD ($) $ / shares
Pension Plan [Line Items]
Service cost for benefits earned during the period	$ 2,349	$ 1,897	$ 7,121	$ 6,230
Interest cost on pension benefit obligation	5,119	5,852	15,515	19,218
Expected return on assets	(6,871)	(6,945)	(20,826)	(22,806)
Amortization of unrecognized losses	2,110	1,493	6,395	4,902
Net periodic pension cost	$ 2,707	2,297	$ 8,205	7,544
Incentive Compensation [Line Items]
Common Stock, par value | $ / shares	$ 0.01		$ 0.01				$ 0.01
Stock based compensation expense	$ 6,300	5,200	$ 16,641	13,651
Restricted stock grants- shares | shares			213,349
Restricted stock grants- fair value | $ / shares			$ 56.76
Stock option grants- shares | shares			740,718
Risk free interest rate			1.62%
Expected life (years)			5 years
Volatility			28.10%
Dividend yield			3.14%
Weighted average exercise price of options granted | $ / shares			$ 57.52
Weighted average grant-date fair value of options granted | $ / shares			$ 10.71
Performance cash compensation liability	17,400		$ 17,400				$ 21,000
Performance cash compensation expense	$ 2,800	$ 4,300	$ 4,500	$ 11,300
Plan 2007
Incentive Compensation [Line Items]
Common Stock shares reserved | shares	5,400,000		5,400,000
Shares available for grant | shares	1,449,024		1,449,024
Pension Plan | UK Staff pension plan
Pension Plan [Line Items]
Cash contributions						£ 12.5	$ 18,600
Pension Plan | U.K. pension plans
Pension Plan [Line Items]
Cash contributions			$ 7,300
Pension Plan | U.K. pension plans | Forecast
Pension Plan [Line Items]
Estimated cash contributions					$ 18,100
Pension Plan | Norwegian pension plan
Pension Plan [Line Items]
Cash contributions			$ 6,300
Pension Plan | Norwegian pension plan | Forecast
Pension Plan [Line Items]
Estimated cash contributions					$ 11,700