Derivative Financial Instruments - Summary of Outstanding Forward Foreign Currency Contracts by Currency (Detail) € in Thousands, £ in Thousands, $ in Thousands, $ in Thousands	Mar. 31, 2024 EUR (€)	Mar. 31, 2024 USD ($)	Mar. 31, 2024 GBP (£)	Mar. 31, 2024 SGD ($)	Sep. 30, 2023 EUR (€)	Sep. 30, 2023 USD ($)	Sep. 30, 2023 GBP (£)	Sep. 30, 2023 SGD ($)
Foreign Exchange Contracts To Sell European Euro for US Dollar
Derivative [Line Items]
Fair value of forward foreign currency contracts to sell and buy foreign currency		$ 0				$ 0
Foreign Exchange Contracts To Sell European Euro for US Dollar | Foreign currency forward contracts | Short | Not Designated as Hedging Instrument
Derivative [Line Items]
Contract amount of forward foreign currency contracts	€ 9,000	9,718			€ 12,900	13,621
Foreign Exchange Contracts To Purchase British Pounds With US Dollars
Derivative [Line Items]
Fair value of forward foreign currency contracts to sell and buy foreign currency		0				0
Foreign Exchange Contracts To Purchase British Pounds With US Dollars | Foreign currency forward contracts | Short | Not Designated as Hedging Instrument
Derivative [Line Items]
Contract amount of forward foreign currency contracts		12,200	£ 9,670			13,100	£ 10,700
Foreign Exchange Contracts To Purchase Singapore Dollars With US Dollars
Derivative [Line Items]
Fair value of forward foreign currency contracts to sell and buy foreign currency		0				0
Foreign Exchange Contracts To Purchase Singapore Dollars With US Dollars | Foreign currency forward contracts | Short | Not Designated as Hedging Instrument
Derivative [Line Items]
Contract amount of forward foreign currency contracts		$ 7,800		$ 10,487		$ 6,300		$ 8,569