Derivative Instruments - Notional Amounts Outstanding under Foreign Currency Contracts (Detail) - Not Designated as Hedging Instrument - Foreign Exchange Contract - USD ($) $ in Thousands	Dec. 31, 2016	Sep. 30, 2016
Derivative [Line Items]
Fair Value of Assets	$ 34	$ 5
Fair Value of Liabilities	(86)	(96)
Buy Currency, British Pound; Sell Currency, Norwegian Krone
Derivative [Line Items]
Fair Value of Assets	0
Fair Value of Liabilities	0
Buy Currency, British Pound; Sell Currency, Norwegian Krone | Long
Derivative [Line Items]
Notional Amount	115
Buy Currency, British Pound; Sell Currency, Norwegian Krone | Short
Derivative [Line Items]
Notional Amount	1,000
Buy Currency, Japanese Yen; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	0
Fair Value of Liabilities	(2)
Buy Currency, Japanese Yen; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	691
Buy Currency, Japanese Yen; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	81,000
Buy Currency, British Pound; Sell Currency, Swedish Krona
Derivative [Line Items]
Fair Value of Assets	2	1
Fair Value of Liabilities	0	0
Buy Currency, British Pound; Sell Currency, Swedish Krona | Long
Derivative [Line Items]
Notional Amount	936	246
Buy Currency, British Pound; Sell Currency, Swedish Krona | Short
Derivative [Line Items]
Notional Amount	8,600	2,100
Buy Currency, Korean Won; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	0	1
Fair Value of Liabilities	(9)	0
Buy Currency, Korean Won; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	1,711	2,255
Buy Currency, Korean Won; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	2,062,000	2,488,000
Buy Currency, U.S. Dollar; Sell Currency, Taiwan Dollar
Derivative [Line Items]
Fair Value of Assets	0
Fair Value of Liabilities	0
Buy Currency, U.S. Dollar; Sell Currency, Taiwan Dollar | Long
Derivative [Line Items]
Notional Amount	22
Buy Currency, U.S. Dollar; Sell Currency, Taiwan Dollar | Short
Derivative [Line Items]
Notional Amount	700
Buy Currency, U.S. Dollar; Sell Currency, Chinese Yuan
Derivative [Line Items]
Fair Value of Assets	0	0
Fair Value of Liabilities	(70)	(33)
Buy Currency, U.S. Dollar; Sell Currency, Chinese Yuan | Long
Derivative [Line Items]
Notional Amount	5,823	5,815
Buy Currency, U.S. Dollar; Sell Currency, Chinese Yuan | Short
Derivative [Line Items]
Notional Amount	41,000	39,000
Buy Currency, Euro; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	32	0
Fair Value of Liabilities	0	(40)
Buy Currency, Euro; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	12,386	14,976
Buy Currency, Euro; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	11,900	13,300
Buy Currency, U.S. Dollar; Sell Currency, British Pound
Derivative [Line Items]
Fair Value of Assets	0	2
Fair Value of Liabilities	(2)	0
Buy Currency, U.S. Dollar; Sell Currency, British Pound | Long
Derivative [Line Items]
Notional Amount	2,338	6,107
Buy Currency, U.S. Dollar; Sell Currency, British Pound | Short
Derivative [Line Items]
Notional Amount	1,910	4,710
Buy Currency, Singapore Dollar; Sell Currency, U.S. Dollar
Derivative [Line Items]
Fair Value of Assets	0
Fair Value of Liabilities	0
Buy Currency, Singapore Dollar; Sell Currency, U.S. Dollar | Long
Derivative [Line Items]
Notional Amount	261
Buy Currency, Singapore Dollar; Sell Currency, U.S. Dollar | Short
Derivative [Line Items]
Notional Amount	380
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	350	311
Buy Currency, U.S. Dollar; Sell Currency, Israeli Shekel | Short
Derivative [Line Items]
Notional Amount	1,350	1,169
Buy Currency, Euro; Sell Currency, British Pound
Derivative [Line Items]
Fair Value of Assets	0	0
Fair Value of Liabilities	(3)	(23)
Buy Currency, Euro; Sell Currency, British Pound | Long
Derivative [Line Items]
Notional Amount	11,465	8,403
Buy Currency, Euro; Sell Currency, British Pound | Short
Derivative [Line Items]
Notional Amount	$ 9,359	$ 6,500