Derivative Instruments and Hedging Activities - Undesignated Hedges (Detail) (Not Designated as Hedging Instrument [Member], Forward exchange contracts [Member], Other income (expense) [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Not Designated as Hedging Instrument [Member] | Forward exchange contracts [Member] | Other income (expense) [Member]
Derivatives And Hedging Activities [Line Items]
Amount of Gain (Loss) Recognized in Income on Derivative	$ (8,838)	$ 8,903	$ 4,246	$ 6,039