Marketable Securities (Tables)

6 Months Ended

Mar. 31, 2018

Investments, Debt and Equity Securities [Abstract]

Summary of Marketable Securities Including Accrued Interest Receivable

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 March 31, 2018 and September 30, 2017 (in thousands):

			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Losses		Gains		Fair Value
March 31, 2018 :
U.S. Treasury securities and obligations of U.S. government agencies	$	31,870	$	(56)	$	—	$	31,814
Bank certificates of deposits		6,158		—		2		6,160
Corporate securities		6,426		(17)		—		6,409
Municipal securities		6,761		(10)		—		6,751
Other debt securities		29		—		—		29
	$	51,244	$	(83)	$	2	$	51,163
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 March 31, 2018 are presented below (in thousands):

	Fair Value
Due in one year or less	$	40,655
Due after one year through five years		7,785
Due after five year through ten years		—
Due after ten years		2,723
Total marketable securities	$	51,163