Investments (Tables)

9 Months Ended

Jun. 30, 2018

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, 2018
(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Short-term commercial paper and corporate    bonds	$	34,814	$	—	$	(54	)	$	34,760
Long-term corporate bonds		—		—		—			—
Total	$	34,814	$	—	$	(54	)	$	34,760

	September 30, 2017
(Dollars in thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
Short-term commercial paper and corporate    bonds	$	31,817	$	—	$	(15	)	$	31,802
Total	$	31,817	$	—	$	(15	)	$	31,802