Investments (Tables)

9 Months Ended

Jun. 30, 2017

Investments Debt And Equity Securities [Abstract]

Amortized Cost, Unrealized Holding Gains and (Losses) and Fair Value of Available-for-sale Securities

The amortized cost, unrealized holding gains and losses, and fair value of available-for-sale securities were as follows:    

	June 30, 2017
(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Commercial paper and corporate bonds	$	32,382	$	—	$	(22	)	$	32,360
Total	$	32,382	$	—	$	(22	)	$	32,360

	September 30, 2016
(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Commercial paper and corporate bonds	$	22,019	$	—	$	(65	)	$	21,954
Total	$	22,019	$	—	$	(65	)	$	21,954

Sales of Available-for-Sale Debt Securities

The following table summarizes sales of available-for-sale debt securities:

	Three Months Ended				Nine Months Ended
	June 30,				June 30,
(Dollars in thousands)	2017		2016		2017		2016
Proceeds from maturities	$	17,500	$	—	$	44,571	$	—
Gross realized gains		—		—		—		—
Gross realized losses		—		—		—		—