Other Financial Instruments and Fair Value Measurements (Detalis 1) (Fair value measurements recurring [Member], USD $) In Thousands, unless otherwise specified	Oct. 31, 2011		Apr. 30, 2011
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities	$ 0	[1]	$ 18,600	[1]
Total Financial Assets Measured at Fair Value	37,572		69,175
Equity mutual funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	11,876	[2]	14,011	[2]
Municipal obligations [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	20,681	[2]	20,042	[2]
Other investments [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	7,579	[2]	7,507	[2]
Commodity contracts [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	(2,537)	[3]	7,863	[3]
Foreign currency exchange contracts [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	(27)	[3]	(2,887)	[3]
Interest rate contract [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	0	[3]	4,039	[3]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities	0	[1]
Total Financial Assets Measured at Fair Value	9,848
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Equity mutual funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	11,876	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Municipal obligations [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	0	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other investments [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	536	[2]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Commodity contracts [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	(2,537)	[3]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Foreign currency exchange contracts [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	(27)	[3]
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Interest rate contract [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	0	[3]
Significant Observable Inputs (Level 2) [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities	0	[1]
Total Financial Assets Measured at Fair Value	27,724
Significant Observable Inputs (Level 2) [Member] | Equity mutual funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	0	[2]
Significant Observable Inputs (Level 2) [Member] | Municipal obligations [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	20,681	[2]
Significant Observable Inputs (Level 2) [Member] | Other investments [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	7,043	[2]
Significant Observable Inputs (Level 2) [Member] | Commodity contracts [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	0	[3]
Significant Observable Inputs (Level 2) [Member] | Foreign currency exchange contracts [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	0	[3]
Significant Observable Inputs (Level 2) [Member] | Interest rate contract [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	0	[3]
Significant Unobservable Inputs (Level 3) [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Marketable securities	0	[1]
Total Financial Assets Measured at Fair Value	0
Significant Unobservable Inputs (Level 3) [Member] | Equity mutual funds [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	0	[2]
Significant Unobservable Inputs (Level 3) [Member] | Municipal obligations [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	0	[2]
Significant Unobservable Inputs (Level 3) [Member] | Other investments [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Other investments	0	[2]
Significant Unobservable Inputs (Level 3) [Member] | Commodity contracts [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	0	[3]
Significant Unobservable Inputs (Level 3) [Member] | Foreign currency exchange contracts [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	0	[3]
Significant Unobservable Inputs (Level 3) [Member] | Interest rate contract [Member]
Financial assets (liabilities) measured at fair value on a recurring basis
Derivative	$ 0	[3]

[1] The Company?s marketable securities consisted entirely of commercial paper at April 30, 2011, and were broker-priced and valued by a third party using an evaluated pricing methodology. An evaluated pricing methodology is a valuation technique which uses inputs that are derived principally from or corroborated by observable market data. All securities had matured or were sold prior to October 31, 2011.

[2] The Company?s other investments consist of funds maintained for the payment of benefits associated with nonqualified retirement plans. The funds include equity securities listed in active markets and municipal obligations valued by a third party using an evaluated pricing methodology. As of October 31, 2011, the Company?s municipal obligations are scheduled to mature as follows: $647 in 2012, $3,371 in 2013, $742 in 2014, $2,766 in 2015, and $13,155 in 2016 and beyond.

[3] The Company?s commodity contract and foreign currency exchange contract derivatives are valued using quoted market prices. The Company?s interest rate contract derivative was valued using the income approach, observable Level 2 market expectations at the measurement date, and standard valuation techniques to convert future amounts to a single discounted present value. Level 2 inputs for the interest rate contract are limited to quoted prices for similar assets or liabilities in active markets and inputs other than quoted prices that are observable for the asset or liability. For additional information, see Note M ? Derivative Financial Instruments.