Derivative Instruments and Hedging Activities - Effects on Consolidated Balance Sheets (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012
Derivatives, Fair Value [Line Items]
Asset derivatives	$ 21,680	$ 19,550
Liability derivatives	15,955	18,229
Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives	1,505	2,353
Designated as Hedging Instrument [Member] | Interest rate swaps [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives	193	2,353
Designated as Hedging Instrument [Member] | Commodity forward contracts [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives	1,312
Liability derivatives		1,666
Not Designated as Hedging Instrument [Member] | Forward exchange contracts [Member]
Derivatives, Fair Value [Line Items]
Asset derivatives	20,175	17,197
Liability derivatives	$ 15,955	$ 16,563