During the three months ended March 31, 2020, the Company transferred all of its investment securities classified as held to maturity to available for sale in order to provide maximum flexibility to address liquidity and capital needs that may result from COVID-19. The Company believes that these transfers are allowable under existing GAAP due to the isolated, non-recurring and unusual events resulting from the pandemic.

The following tables summarize the amortized cost and fair value of securities available for sale as of March 31, 2020, and the amortized cost and fair value of securities held to maturity and available for sale, respectively, as of December 31, 2019 and the corresponding amounts of gross unrealized gains and losses:

March 31, 2020	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available for sale:
Corporate bonds	$	19,648	$	144	$	103	$	19,689
Municipal securities		170,561		3,276		288		173,549
Mortgage-backed securities		93,979		2,508		67		96,420
Collateralized mortgage obligations		87,001		487		84		87,404
Total available for sale	$	371,189	$	6,415	$	542	$	377,062

December 31, 2019	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value
Available for sale:
Corporate bonds	$	19,667	$	592	$	—	$	20,259
Municipal securities		16,780		576		8		17,348
Mortgage-backed securities		83,967		550		335		84,182
Collateralized mortgage obligations		89,798		1,146		17		90,927
Total available for sale	$	210,212	$	2,864	$	360	$	212,716

Held to maturity:
Municipal securities	$	138,416	$	4,710	$	3	$	143,123
Mortgage-backed securities		14,365		198		13		14,550
Collateralized mortgage obligations		2,677		110		—		2,787
Total held to maturity	$	155,458	$	5,018	$	16	$	160,460

There is no allowance for credit losses recorded for our available for sale debt securities as of March 31, 2020.

For the year ended December 31, 2019, management evaluated securities for other-than-temporary impairment (“OTTI”) on at least a quarterly basis, and more frequently when economic or market concerns warranted such evaluation. Consideration was given to (1) the length of time and the extent to which the fair value has been less than cost, (2) the financial condition and near-term prospects of the issuer, and (3) the intent and ability of the Company to retain its investment in the issuer for a period of time sufficient to allow for any anticipated recovery in fair value. The Company did not record any OTTI losses on any of its securities for the year ended December 31, 2019.

Information pertaining to securities with gross unrealized losses as of March 31, 2020, for which no allowance for credit losses has been recorded, and December 31, 2019, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position is detailed in the following tables:

	Less Than 12 Months					12 Months or Longer					Total
March 31, 2020	Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value
Available for sale:
Corporate bonds	$	(103	)	$	11,430	$	—		$	—	$	(103	)	$	11,430
Municipal securities		(288	)		28,772		—			—		(288	)		28,772
Mortgage-backed securities		(13	)		4,233		(54	)		5,840		(67	)		10,073
Collateralized mortgage obligations		(66	)		26,914		(18	)		2,261		(84	)		29,175
Total available for sale	$	(470	)	$	71,349	$	(72	)	$	8,101	$	(542	)	$	79,450

	Less Than 12 Months					12 Months or Longer					Total
December 31, 2019	Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value		Gross Unrealized Losses			Estimated Fair Value
Available for sale:
Corporate bonds	$	—		$	—	$	—		$	—	$	—		$	—
Municipal securities		(8	)		1,138		—			—		(8	)		1,138
Mortgage-backed securities		(25	)		19,421		(310	)		42,116		(335	)		61,537
Collateralized mortgage obligations		—			—		(17	)		2,594		(17	)		2,594
Total available for sale	$	(33	)	$	20,559	$	(327	)	$	44,710	$	(360	)	$	65,269

Held to maturity:
Municipal securities	$	(1	)	$	1,313	$	(2	)	$	759	$	(3	)	$	2,072
Mortgage-backed securities		—			—		(13	)		7,032		(13	)		7,032
Collateralized mortgage obligations		—			—		—			—		—			—
Total held to maturity	$	(1	)	$	1,313	$	(15	)	$	7,791	$	(16	)	$	9,104

The number of investment positions in an unrealized loss position with no recorded allowance for credit losses totaled 66 at March 31, 2020. The securities in a loss position were composed of tax-exempt municipal bonds, corporate bonds, collateralized mortgage obligations and mortgage backed securities. Management evaluates available for sale debt securities in an unrealized loss position to determine whether the impairment is due to credit-related factors or noncredit-related factors. With respect to U.S. Government agency securities, the Company has determined that a decline in fair value is not due to credit-related factors. The Company monitors the credit quality of other debt securities through the use of credit ratings and other factors specific to an individual security in assessing whether or not the decline in fair value of municipal or corporate securities, relative to their amortized cost, is due to credit-related factors. Triggers to prompt further investigation of securities when the fair value is less than the amortized cost are when a security has been downgraded and falls below an A credit rating, and the security’s unrealized loss exceeds 20% of its book value. Consideration is given to (1) the extent to which fair value is less than cost, (2) the financial condition and near-term prospects of the issuer, and (3) the intent and ability of the Company to retain its investment in the security for a period of time sufficient to allow for any anticipated recovery in fair value. Based on evaluation of available evidence, management believes the unrealized loss on the securities as of March 31, 2020 is not credit-related. Management does not have the intent to sell any of these securities and believes that it is more likely than not the Company will not have to sell any such securities before recovery of cost. The fair values are expected to recover as the securities approach their maturity date or repricing date or if market yields for the investments decline.

Mortgage-backed securities and collateralized mortgage obligations are backed by pools of mortgages that are insured or guaranteed by the Federal Home Loan Mortgage Corporation, the Federal National Mortgage Association or the Government National Mortgage Association.

As of March 31, 2020, there were no holdings of securities of any one issuer, other than the U.S. government and its agencies, in an amount greater than 10% of shareholders’ equity.

Securities with fair values of approximately $300,214 and $278,318 at March 31, 2020 and December 31, 2019, respectively, were pledged to secure public fund deposits and for other purposes as required or permitted by law.

There were no securities sold during the three months ended March 31, 2020 or 2019.

The contractual maturities at March 31, 2020 of available for sale securities at carrying value and estimated fair value are shown below. The Company invests in mortgage-backed securities and collateralized mortgage obligations that have expected maturities that differ from their contractual maturities. These differences arise because borrowers and/or issuers may have the right to call or prepay their obligation with or without call or prepayment penalties.

	Available for Sale
March 31, 2020	Amortized Cost		Estimated Fair Value
Due within one year	$	5,095	$	5,115
Due after one year through five years		51,142		51,724
Due after five years through ten years		51,401		52,805
Due after ten years		82,571		83,594
Mortgage-backed securities		93,979		96,420
Collateralized mortgage obligations		87,001		87,404
Total securities	$	371,189	$	377,062