FINANCIAL INSTRUMENTS (Details) In Thousands, unless otherwise specified	0 Months Ended								3 Months Ended		6 Months Ended
	Dec. 01, 2009 Derivatives not designated as hedging instrument [Member] Canadian debt interest rate swap derivative [Member] CAD	Feb. 15, 2008 Derivatives not designated as hedging instrument [Member] Canadian debt interest rate swap derivative [Member] CAD	Feb. 15, 2008 Derivatives not designated as hedging instrument [Member] Canadian debt interest rate swap derivative [Member] Canadian BA Rate [Member]	Feb. 15, 2008 Derivatives not designated as hedging instrument [Member] US debt interest rate swap derivative [Member] USD ($)	Feb. 15, 2008 Derivatives not designated as hedging instrument [Member] US debt interest rate swap derivative [Member] LIBOR [Member]	Sep. 30, 2012 Interest rate swap contracts [Member] interest_rate_swap_contracts	Sep. 30, 2012 Interest rate swap contracts [Member] Derivatives not designated as hedging instrument [Member] interest_rate_swap_contracts	Mar. 31, 2012 Interest rate swap contracts [Member] Derivatives not designated as hedging instrument [Member] interest_rate_swap_contracts	Sep. 30, 2012 Interest rate swap contracts [Member] Derivatives not designated as hedging instrument [Member] Other (income) and expenses [Member] USD ($)	Sep. 30, 2011 Interest rate swap contracts [Member] Derivatives not designated as hedging instrument [Member] Other (income) and expenses [Member] USD ($)	Sep. 30, 2012 Interest rate swap contracts [Member] Derivatives not designated as hedging instrument [Member] Other (income) and expenses [Member] USD ($)	Sep. 30, 2011 Interest rate swap contracts [Member] Derivatives not designated as hedging instrument [Member] Other (income) and expenses [Member] USD ($)	Sep. 30, 2012 Interest rate swap contracts [Member] Derivatives not designated as hedging instrument [Member] Current liability [Member] USD ($)	Mar. 31, 2012 Interest rate swap contracts [Member] Derivatives not designated as hedging instrument [Member] Current liability [Member] USD ($)	Sep. 30, 2012 Quoted prices in active markets (Level 1) [Member] Interest rate swap contracts [Member] Recurring basis [Member] Derivatives not designated as hedging instrument [Member] USD ($)	Mar. 31, 2012 Quoted prices in active markets (Level 1) [Member] Interest rate swap contracts [Member] Recurring basis [Member] Derivatives not designated as hedging instrument [Member] USD ($)	Sep. 30, 2012 Significant other observable inputs (Level 2) [Member] Interest rate swap contracts [Member] Recurring basis [Member] Derivatives not designated as hedging instrument [Member] USD ($)	Mar. 31, 2012 Significant other observable inputs (Level 2) [Member] Interest rate swap contracts [Member] Recurring basis [Member] Derivatives not designated as hedging instrument [Member] USD ($)	Sep. 30, 2012 Carrying value [Member] Interest rate swap contracts [Member] Recurring basis [Member] Derivatives not designated as hedging instrument [Member] USD ($)	Mar. 31, 2012 Carrying value [Member] Interest rate swap contracts [Member] Recurring basis [Member] Derivatives not designated as hedging instrument [Member] USD ($)
Derivative [Line Items]
Interest rate swap contracts liability															$ 0	$ 0	$ 549	$ 1,088	$ 549	$ 1,088
Number of interest rate swap contracts						2	2	2
Resulting gain from fair value adjustment									(272)	46	(542)	(91)
Amount of interest rate derivative		49,700		22,000
Fixed interest rate		4.09%		3.65%
Amount of hedged item		49,700		22,000
Measurement period of variable rate			3 months		3 months
Decrease in amount of hedged item	15,000
Interest rate swap contracts liability, fair value													$ 549	$ 1,088