Fair Value (Details) (USD $) In Thousands, unless otherwise specified			6 Months Ended
Oct. 31, 2012	Apr. 30, 2012	Oct. 31, 2012 Fair Value, Inputs, Level 3 [Member]
Balance, May 1, 2012	$ 322	$ 555	$ 555
Transfers to (from) Level 3			0
Total (gains) losses included in earnings			(233)
Purchases, issuances and settlements, net			0
Balance, October 31, 2012	$ 322	$ 555	$ 322

Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be extinguished or otherwise disposed of after one year or beyond the normal operating cycle, if longer, net of the effects of master netting arrangements.

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+ Details