Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Marketable securities

The following table summarizes the proceeds from the maturities of available-for-sale securities for the three and nine months ended September 30, 2018 and 2019 (in thousands):

	For the three months ended September 30,				For the nine months ended September 30,
	2018		2019		2018		2019
Maturities of marketable securities	$	5,842	$	10,300	$	5,842	$	32,860
Total	$	5,842	$	10,300	$	5,842	$	32,860

Schedule for Available-for-Sale Securities

The following is a summary of available-for-sale securities as of September 30, 2019 (in thousands):

	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Losses)			Estimated Fair Value
Corporate debt securities	$	40,148	$	207	$	(6	)	$	40,349
Tax-exempt municipal securities	13,936		131		(29		)	14,038
Variable rate demand notes	5,600		—		—			5,600
Total	$	59,684	$	338	$	(35	)	$	59,987

The following is a summary of available-for-sale securities as of December 31, 2018 (in thousands):

	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Losses)			Estimated Fair Value
Corporate debt securities	$	48,202	$	12	$	(284	)	$	47,930
Tax-exempt municipal securities	22,858		45		(34		)	22,869
Variable rate demand notes	4,000		—		—			4,000
Total	$	75,060	$	57	$	(318	)	$	74,799

Schedule of Maturities of Marketable Securities

The following table summarizes the maturities of the Company’s marketable securities as of December 31, 2018 and September 30, 2019 (in thousands):

	December 31, 2018		September 30, 2019
Due within one year	$	37,121	$	33,455
Due after one year through five years	37,678		26,532
Total	$	74,799	$	59,987