EMPLOYEE BENEFIT PLANS (Details) (USD $)	3 Months Ended		6 Months Ended				12 Months Ended	6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Mar. 31, 2013	Sep. 30, 2013 Plan 2007 [Member]	Mar. 31, 2013 UK staff pension plan [Member]	Sep. 30, 2013 Norway pension plan [Member]	Mar. 31, 2014 Norway pension plan [Member]	Sep. 30, 2013 UK Pension Plans [Member]	Mar. 31, 2014 UK Pension Plans [Member]
Pension Plan [Line Items]
Service cost	$ 2,070,000	$ 2,052,000	$ 4,121,000	$ 4,109,000
Interest cost	6,602,000	6,418,000	13,140,000	12,851,000
Expected return on assets	(7,171,000)	(7,264,000)	(14,273,000)	(14,545,000)
Amortization of unrecognized losses	1,897,000	1,652,000	3,774,000	3,309,000
Net periodic pension cost	3,398,000	2,858,000	6,762,000	5,724,000
Cash Contributions							19,000,000	5,500,000		9,400,000
Estimated cash contributions									8,100,000		15,500,000
Incentive Compensation [Line Items]
Common Stock Shares reserved						5,400,000
Shares available for grant						3,022,768
Stock based compensation expense	3,700,000	2,700,000	6,625,000	5,523,000
Stock option grants- shares			302,678
Restricted stock grants- shares			179,821
Restricted stock grants- fair value			$ 63.19
Risk free interest rate			1.01%
Expected life (years)			5 years
Volatility			48.70%
Dividend yield			1.60%
Weighted average exercise price of options granted			$ 62.66
Weighted average grant-date fair value of options granted			$ 23.77
Performance cash compensation liability	11,800,000		11,800,000		13,400,000
Performance cash compensation expense	$ 1,900,000	$ 3,400,000	$ 3,700,000	$ 4,100,000