Investments (Tables)

6 Months Ended

Mar. 31, 2021

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:

	March 31, 2021
	Valuation									Balance Sheet Classification
(In thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value		Current Assets		Noncurrent Assets
Commercial paper and     corporate bonds	$	21,870	$	1	$	(8	)	$	21,863	$	17,792	$	4,071
Total	$	21,870	$	1	$	(8	)	$	21,863	$	17,792	$	4,071

	September 30, 2020
	Valuation									Balance Sheet Classification
(In thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value		Current Assets		Noncurrent Assets
Commercial paper and     corporate bonds	$	30,313	$	19	$	(19	)	$	30,313	$	30,313	$	—
Total	$	30,313	$	19	$	(19	)	$	30,313	$	30,313	$	—