Derivative Financial Instruments (Tables)

12 Months Ended

Sep. 30, 2019

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Notional Amounts of Outstanding Derivative Positions

The following tables summarize our outstanding foreign currency forward contracts, by currency at September 30, 2019 and 2018: 

	September 30, 2019
	Contract Amount				Fair Value
	Foreign Currency		US$		US$
		(In thousands)
Sell foreign currency:
Euro (EUR)	EUR	10,800	$	11,723	—
Buy foreign currency:
British pound (GBP)	GBP	5,200	$	6,400	—
Singapore dollar (SGD)	SGD	5,798	$	4,200	—

	September 30, 2018
	Contract Amount				Fair Value
	Foreign Currency		US$		US$
		(In thousands)
Sell foreign currency:
Euro (EUR)	EUR	9,000	$	10,372	—
Buy foreign currency:
British pound (GBP)	GBP	8,598	$	11,200	—
Singapore dollar (SGD)	SGD	9,580	$	7,000	—

Schedule of Derivative Instruments, Gain (Loss) in Statement of Financial Performance

These amounts are shown below for the years ended September 30, 2019, 2018 and 2017: 

	Year Ended September 30,
	2019			2018			2017
	(In thousands)
Gain (loss) on foreign currency forward contracts	$	(896	)	$	(476	)	$	210