Summary of Outstanding Forward Foreign Currency Contracts by Currency (Detail) In Thousands, unless otherwise specified	Dec. 31, 2012 Foreign Exchange Contracts to Sell Canadian Dollar for US Dollar USD ($)	Sep. 30, 2012 Foreign Exchange Contracts to Sell Canadian Dollar for US Dollar USD ($)	Dec. 31, 2012 Foreign Exchange Contracts to Sell Canadian Dollar for US Dollar Not Designated as Hedging Instrument USD ($)	Dec. 31, 2012 Foreign Exchange Contracts to Sell Canadian Dollar for US Dollar Not Designated as Hedging Instrument CAD	Sep. 30, 2012 Foreign Exchange Contracts to Sell Canadian Dollar for US Dollar Not Designated as Hedging Instrument USD ($)	Sep. 30, 2012 Foreign Exchange Contracts to Sell Canadian Dollar for US Dollar Not Designated as Hedging Instrument CAD	Dec. 31, 2012 Foreign Exchange Contracts To Sell European Euro for US Dollar USD ($)	Sep. 30, 2012 Foreign Exchange Contracts To Sell European Euro for US Dollar USD ($)	Dec. 31, 2012 Foreign Exchange Contracts To Sell European Euro for US Dollar Not Designated as Hedging Instrument USD ($)	Dec. 31, 2012 Foreign Exchange Contracts To Sell European Euro for US Dollar Not Designated as Hedging Instrument EUR (€)	Sep. 30, 2012 Foreign Exchange Contracts To Sell European Euro for US Dollar Not Designated as Hedging Instrument USD ($)	Sep. 30, 2012 Foreign Exchange Contracts To Sell European Euro for US Dollar Not Designated as Hedging Instrument EUR (€)	Dec. 31, 2012 Foreign Exchange Contracts To Purchase British Pounds With US Dollars USD ($)	Sep. 30, 2012 Foreign Exchange Contracts To Purchase British Pounds With US Dollars USD ($)	Dec. 31, 2012 Foreign Exchange Contracts To Purchase British Pounds With US Dollars Not Designated as Hedging Instrument USD ($)	Dec. 31, 2012 Foreign Exchange Contracts To Purchase British Pounds With US Dollars Not Designated as Hedging Instrument GBP (£)	Sep. 30, 2012 Foreign Exchange Contracts To Purchase British Pounds With US Dollars Not Designated as Hedging Instrument USD ($)	Sep. 30, 2012 Foreign Exchange Contracts To Purchase British Pounds With US Dollars Not Designated as Hedging Instrument GBP (£)
Derivative [Line Items]
Contract amount of forward foreign currency contracts to sell foreign currency			$ 4,708	4,700	$ 2,794	2,750			$ 7,033	€ 5,350	$ 5,255	€ 4,060
Contract amount of forward foreign currency contracts to buy foreign currency															8,050	4,983	9,950	6,131
Fair value of forward foreign currency contracts to sell and buy foreign currency