Marketable Securities (Tables)

9 Months Ended

Jun. 30, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost and Fair Value, Including Accrued Interest Receivable and Unrealized Holding Gains (Losses) on Short-term and Long-term Marketable Securities

The following is a summary of the amortized cost and the fair value, including accrued interest receivable and unrealized holding gains (losses) on the short-term and long-term marketable securities as of June 30, 2018 and September 30, 2017 (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Losses		Gains		Fair Value
June 30, 2018 :
U.S. Treasury securities and obligations of U.S. government agencies	$	33,547	$	(63)	$	—	$	33,484
Bank certificates of deposits		5,889		—		1		5,890
Corporate securities		9,298		(18)		—		9,280
Municipal securities		3,216		(17)		—		3,199
Other debt securities		754		—		—		754
	$	52,704	$	(98)	$	1	$	52,607
September 30, 2017 :
Corporate securities	$	2,642	$	—	$	—	$	2,642
Other debt securities		28		—		—		28
	$	2,670	$	—	$	—	$	2,670

Fair Value of Marketable Securities by Contractual Maturity

The fair values of the marketable securities by contractual maturities at June 30, 2018 are presented below (in thousands):

	Fair Value
Due in one year or less	$	42,096
Due after one year through five years		7,753
Due after five years through ten years		—
Due after ten years		2,758
Total marketable securities	$	52,607