Marketable Securities (Tables)

12 Months Ended

Sep. 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, as well as unrealized holding gains (losses) on the short-term and long-term marketable securities as of September 30, 2018 and 2017 (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Losses		Gains		Fair Value
September 30, 2018:
U.S. Treasury securities and obligations of U.S. government agencies	$	30,142	$	(65)	$	—	$	30,077
Bank certificates of deposits		5,148		—		1		5,149
Corporate securities		14,763		(30)		—		14,733
Municipal securities		2,797		(17)		—		2,780
Other debt securities		779		—		—		779
	$	53,629	$	(112)	$	1	$	53,518
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 September 30, 2018 are presented below (in thousands).

	Fair Value
Due in one year or less	$	46,281
Due after one year through five years		4,373
Due after five years through ten years		—
Due after ten years		2,864
Total marketable securities	$	53,518