Derivative Financial Instruments - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Dec. 31, 2012
Derivative Financial Instruments [Line Items]
Foreign currency hedge arrangements	Dec. 31, 2012
Accrued unrealized foreign exchange losses	$ 0.2
Foreign Exchange Contract
Derivative Financial Instruments [Line Items]
Foreign currency forward contract to hedge	18.0
Canadian Subsidiary
Derivative Financial Instruments [Line Items]
Denominated intercompany accounts payable	$ 34.4