Derivative Instruments - Notional Amounts Outstanding under Foreign Currency Contracts (Detail) - Not Designated as Hedging Instrument - Foreign Exchange Contract - USD ($) $ in Thousands	Mar. 31, 2017	Sep. 30, 2016
Derivative [Line Items]
Fair Value of Assets	$ 57	$ 5
Fair Value of Liabilities	(150)	(96)
Buy Currency, Japanese Yen; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	0
Fair Value of Liabilities	(24)
Buy Currency, Japanese Yen; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	1,772
Buy Currency, Japanese Yen; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	193,000
Buy Currency, British Pound; Sell Currency, Swedish Krona
Derivative [Line Items]
Fair Value of Assets	0	1
Fair Value of Liabilities	0	0
Buy Currency, British Pound; Sell Currency, Swedish Krona | Long
Derivative [Line Items]
Notional Amount	11	246
Buy Currency, British Pound; Sell Currency, Swedish Krona | Short
Derivative [Line Items]
Notional Amount	100	2,100
Buy Currency, Korean Won; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	0	1
Fair Value of Liabilities	(29)	0
Buy Currency, Korean Won; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	2,896	2,255
Buy Currency, Korean Won; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	3,190,000	2,488,000
Buy Currency, Taiwan Dollar; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	0
Fair Value of Liabilities	(9)
Buy Currency, Taiwan Dollar; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	280
Buy Currency, Taiwan Dollar; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	8,200
Buy Currency, U.S. Dollar; Sell Currency, Chinese Yuan
Derivative [Line Items]
Fair Value of Assets	10	0
Fair Value of Liabilities	0	(33)
Buy Currency, U.S. Dollar; Sell Currency, Chinese Yuan | Long
Derivative [Line Items]
Notional Amount	5,688	5,815
Buy Currency, U.S. Dollar; Sell Currency, Chinese Yuan | Short
Derivative [Line Items]
Notional Amount	39,000	39,000
Buy Currency, Euro; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	0	0
Fair Value of Liabilities	(3)	(40)
Buy Currency, Euro; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	1,849	14,976
Buy Currency, Euro; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	1,700	13,300
Buy Currency, U.S. Dollar; Sell Currency, British Pound
Derivative [Line Items]
Fair Value of Assets	46	2
Fair Value of Liabilities	0	0
Buy Currency, U.S. Dollar; Sell Currency, British Pound | Long
Derivative [Line Items]
Notional Amount	6,347	6,107
Buy Currency, U.S. Dollar; Sell Currency, British Pound | Short
Derivative [Line Items]
Notional Amount	5,020	4,710
Buy Currency, Singapore Dollar; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	1
Fair Value of Liabilities	0
Buy Currency, Singapore Dollar; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	264
Buy Currency, Singapore Dollar; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	370
Buy Currency, U.S. Dollar; Sell Currency, Israeli Shekel
Derivative [Line Items]
Fair Value of Assets	0	1
Fair Value of Liabilities	0	0
Buy Currency, U.S. Dollar; Sell Currency, Israeli Shekel | Long
Derivative [Line Items]
Notional Amount	261	311
Buy Currency, U.S. Dollar; Sell Currency, Israeli Shekel | Short
Derivative [Line Items]
Notional Amount	947	1,169
Buy Currency, Euro; Sell Currency, British Pound
Derivative [Line Items]
Fair Value of Assets	0	0
Fair Value of Liabilities	(85)	(23)
Buy Currency, Euro; Sell Currency, British Pound | Long
Derivative [Line Items]
Notional Amount	19,087	8,403
Buy Currency, Euro; Sell Currency, British Pound | Short
Derivative [Line Items]
Notional Amount	$ 17,499	$ 6,500