Effect of Interest Rate Contracts on the Statement of Operations (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
The Effect of Interest Rate Contracts on the Statements of Operations
Interest expense resulting from derivatives	$ 4,628	$ 5,911	$ 11,465	$ 11,701
(Gain) loss recognized in AOCI on interest rate contracts (effective portion)			(253)	16,110
(Gain) loss reclassified from AOCI into income (effective portion)			10,225	12,048
(Gain) loss recognized in income on interest rate contracts (ineffective portion and amount excluded from effectiveness testing)			$ 1,240	$ (347)

The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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The portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments representing (a) the amount of the hedge ineffectiveness and (b) the amount, if any, excluded from the assessment of hedge effectiveness.

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- Definition

The amount of net gains and losses recognized in income during the period on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges, on derivative instruments designated and qualifying as hedging instruments in cash flow hedges, and on derivative instruments not designated as hedging instruments.

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- Definition

The effective portion of gains and losses (net) on derivative instruments designated and qualifying as hedging instruments that was recognized in other comprehensive income during the current period.

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