Marketable Securities

9 Months Ended

Sep. 30, 2020

Investments, Debt and Equity Securities [Abstract]

The following is a summary of available-for-sale securities as of September 30, 2020 (in thousands):


	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Losses)		Estimated Fair Value
Corporate debt securities	$	22,865	$	485	$	—	$	23,350
Tax-exempt municipal securities	21,907		275		(12)		22,170
Variable rate demand notes	5,600		—		—		5,600

Total	$	50,372	$	760	$	(12)	$	51,120

The following is a summary of available-for-sale securities as of December 31, 2019 (in thousands):


	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Losses)		Estimated Fair Value
Corporate debt securities	$	42,584	$	165	$	(40)	$	42,709
Tax-exempt municipal securities	23,301		112		(215)		23,198
Variable rate demand notes	5,600		—		—		5,600
Total	$	71,485	$	277	$	(255)	$	71,507

The unrealized gains and losses on the Company’s investments in corporate debt and municipal securities as of December 31, 2019 and September 30, 2020 were caused by changes in market values primarily due to interest rate changes. As of September 30, 2020, there were no securities in an unrealized loss position for a period longer than twelve months. The Company has no allowance for credit losses related to its available-for-sale securities as all investments are in investment grade securities. The Company does not intend to sell these securities, and it is not more likely than not that the Company will be required to sell these securities prior to the recovery of their amortized cost basis, which may be at maturity. No impairment charges were recorded during the three and nine months ended September 30, 2019 and 2020.

The following table summarizes the maturities of the Company’s marketable securities as of December 31, 2019 and September 30, 2020 (in thousands):


	December 31, 2019		September 30, 2020
Due within one year	$	34,874	$	20,457
Due after one year through five years	36,633		30,663
Total	$	71,507	$	51,120

Amounts due within one year in the table above included $5.6 million of variable rate demand notes, which have contractual maturities ranging from 17 years to 25 years as of September 30, 2020. The variable rate demand notes are floating rate municipal bonds with embedded put options that allow the Company to sell the security at par plus accrued interest on a settlement basis ranging from one day to seven days. The Company has classified these securities based on their effective maturity dates, which range from one day to seven days from the balance sheet date.

The following table summarizes the proceeds from the maturities and sales of available-for-sale securities for the three and nine months ended September 30, 2019 and 2020 (in thousands):


	For the three months ended September 30,				For the nine months ended September 30,
	2019		2020		2019		2020
Maturities of marketable securities	$	10,300	$	3,999	$	32,860	$	21,404
Sales of marketable securities	—		—		—		1,464
Total	$	10,300	$	3,999	$	32,860	$	22,868

The Company recorded approximately $35,000 in gross realized gains in net income during the nine months ended September 30, 2020 related to the sale of marketable securities. The Company did not record any gross realized gains or losses in net income during the three months ended September 30, 2020 and the three and nine months ended September 30, 2019.