Derivative Financial Instruments (Tables)

9 Months Ended

Jun. 30, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Summary of Outstanding Foreign Currency Forward Contracts

The following tables summarize our outstanding foreign currency forward contracts, by currency, at June 30, 2018 and September 30, 2017:

	June 30, 2018
	Contract Amount				Fair Value
	Foreign Currency		US$		US$
	(In thousands)
Sell foreign currency:
Euro (EUR)	EUR	6,300	$	7,344	$	—
Buy foreign currency:
British pound (GBP)	GBP	6,963	$	9,200	$	—
Singapore dollar (SGD)	SGD	8,326	$	6,100	$	—

	September 30, 2017
	Contract Amount				Fair Value
	Foreign Currency		US$		US$
	(In thousands)
Sell foreign currency:
Euro (EUR)	EUR	5,050	$	5,968	$	—
Buy foreign currency:
British pound (GBP)	GBP	9,341	$	12,500	$	—

Losses on Derivative Financial Instruments

Losses on derivative financial instruments are recorded in our condensed consolidated statements of income and comprehensive income as a component of other income, net, and consisted of the following: 

	Quarter Ended June 30,				Nine Months Ended June 30,
	2018		2017		2018		2017
	(In thousands)
Losses on foreign currency forward contracts	$	870	$	—	$	251	$	505