Marketable Securities

3 Months Ended

Mar. 31, 2021

Investments, Debt and Equity Securities [Abstract]

Marketable Securities

Marketable Securities

The following is a summary of available-for-sale securities as of March 31, 2021 (in thousands):

	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Losses)		Estimated Fair Value
Tax-exempt municipal securities	$	18,917	$	324	$	—	$	19,241
Corporate debt securities	16,139		355		—		16,494
Total	$	35,056	$	679	$	—	$	35,735

The following is a summary of available-for-sale securities as of December 31, 2020 (in thousands):

	Amortized Cost		Gross Unrealized Gain		Gross Unrealized (Losses)		Estimated Fair Value
Tax-exempt municipal securities	$	19,924	$	365	$	—	$	20,289
Corporate debt securities	17,086		452		—		17,538
Total	$	37,010	$	817	$	—	$	37,827

The unrealized gains on the Company’s investments in corporate debt and municipal securities as of December 31, 2020 and March 31, 2021 were caused by changes in market values primarily due to interest rate changes. As of March 31, 2021, 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 months ended March 31, 2020 and 2021.

The following table summarizes the maturities of the Company’s marketable securities as of December 31, 2020 and March 31, 2021 (in thousands):

	December 31, 2020		March 31, 2021
Due within one year	$	7,557	$	6,455
Due after one year through five years	30,270		29,280
Total	$	37,827	$	35,735

The following table summarizes the proceeds from the maturities and sales of available-for-sale securities for the three months ended March 31, 2020 and 2021 (in thousands):

	For the three months ended March 31,
	2020		2021
Maturities of marketable securities	$	9,905	$	1,930
Sales of marketable securities	—		—
Total	$	9,905	$	1,930

The Company did not record any gross realized gains or losses in net income during the three months ended March 31, 2020 and 2021.