Other Financial Instruments and Fair Value Measurements (Tables)

9 Months Ended

Jan. 31, 2013

Other Financial Instruments and Fair Value Measurements [Abstract]

Carrying amount and fair value of financial instruments

	January 31, 2013						April 30, 2012
	Carrying Amount			Fair Value			Carrying Amount			Fair Value
Other investments	$	46,259		$	46,259		$	36,173		$	36,173
Derivative financial instruments—net		7,066			7,066			(13,952	)		(13,952	)
Long-term debt		(2,068,508	)		(2,423,370	)		(2,070,543	)		(2,443,514	)

Financial assets (liabilities) measured at fair value on a recurring basis

	Quoted Prices in			Significant			Significant
	Active Markets for			Observable			Unobservable		Fair Value at
	Identical Assets			Inputs			Inputs		January 31,
	(Level 1)			(Level 2)			(Level 3)		2013
Other investments: (A)
Equity mutual funds	$	19,212		$	—		$	—	$	19,212
Municipal obligations		—			26,549			—		26,549
Other investments		498			—			—		498
Derivatives: (B)
Commodity contracts—net		5,868			186			—		6,054
Foreign currency exchange contracts—net		107			905			—		1,012
Long-term debt (C)		(794,049	)		(1,629,321	)		—		(2,423,370	)
Total financial instruments measured at fair value	$	(768,364	)	$	(1,601,681	)	$	—	$	(2,370,045	)
	Quoted Prices in			Significant			Significant
	Active Markets for			Observable			Unobservable		Fair Value at
	Identical Assets			Inputs			Inputs		April 30,
	(Level 1)			(Level 2)			(Level 3)		2012
Other investments: (A)
Equity mutual funds	$	14,649		$	—		$	—	$	14,649
Municipal obligations		—			20,392			—		20,392
Other investments		1,132			—			—		1,132
Derivatives: (B)
Commodity contracts—net		(12,788	)		(618	)		—		(13,406	)
Foreign currency exchange contracts—net		(1	)		(545	)		—		(546	)
Long-term debt (C)		(777,023	)		(1,666,491	)		—		(2,443,514	)
Total financial instruments measured at fair value	$	(774,031	)	$	(1,647,262	)	$	—	$	(2,421,293	)

(A) 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 valuation techniques which utilize inputs that are derived principally from or corroborated by observable market data. As of January 31, 2013, the Company’s municipal obligations are scheduled to mature as follows: $1.1 million in 2013, $0.7 million in 2014, $2.7 million in 2015, $0.5 million in 2016, and $21.5 million in 2017 and beyond.

(B) The Company’s Level 1 derivatives are valued using quoted market prices for identical instruments in active markets. The Level 2 derivatives are valued using 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 13: Derivative Financial Instruments.

(C) The Company’s long-term debt is comprised of public Notes classified as Level 1 and private Senior Notes classified as Level 2. The public Notes are traded in an active secondary market and valued using quoted prices. The value of the private Senior Notes is based on the net present value of each interest and principal payment, calculated utilizing an interest rate derived from a market yield curve. For additional information, see Note 9: Debt and Financing Arrangements.