Fair Value of Derivative Instruments in Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Foreign Exchange Forward | Other Current Assets
Derivatives Fair Value [Line Items]
Derivative Instruments, Assets	$ 1,817	$ 1,757
Foreign Exchange Forward | Other Assets
Derivatives Fair Value [Line Items]
Derivative Instruments, Assets	211	1,334
Foreign Exchange Forward | Other Liabilities
Derivatives Fair Value [Line Items]
Derivative Instruments, Liabilities	2,396	3,380
Foreign Exchange Forward | Accrued Liabilities
Derivatives Fair Value [Line Items]
Derivative Instruments, Liabilities	10,519	11,168
Embedded Derivative Financial Instruments | Other Current Assets
Derivatives Fair Value [Line Items]
Derivative Instruments, Assets	1,598	1,864
Embedded Derivative Financial Instruments | Other Assets
Derivatives Fair Value [Line Items]
Derivative Instruments, Assets	527	621
Embedded Derivative Financial Instruments | Other Liabilities
Derivatives Fair Value [Line Items]
Derivative Instruments, Liabilities	10	119
Embedded Derivative Financial Instruments | Accrued Liabilities
Derivatives Fair Value [Line Items]
Derivative Instruments, Liabilities	$ 651	$ 866