Financial Instruments - Derivative Instruments Notional Amount Outstanding (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Forward Contracts
Schedule Of Information By Major Category Of Credit Derivatives Contracts [Line Items]
Derivative instruments outstanding	$ 417,674	$ 473,600
Currency Swap
Schedule Of Information By Major Category Of Credit Derivatives Contracts [Line Items]
Derivative instruments outstanding	$ 600,000	$ 600,000	$ 600,000