Trading securities are reported on the Company's consolidated statements of condition at fair value. As of December 31, 2020 and 2019, the fair value of the Company's trading securities were $4.2 million and $3.8 million, respectively. These securities are held in a rabbi trust account and invested in mutual funds. The trading securities will be used for future payments associated with the Company’s Executive Deferred Compensation Plan and Director Deferred Compensation Plan.

AFS debt securities are reported on the Company's consolidated statements of condition at fair value. The following table summarizes the amortized cost, estimated fair value and unrealized gains (losses) of AFS debt securities as of the dates indicated:


(In thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
December 31, 2020
Obligations of states and political subdivisions	$	119,608	$	7,627	$	(115)	$	127,120
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises	547,396		19,796		(574)		566,618
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises	399,937		10,652		(135)		410,454
Subordinated corporate bonds	11,533		186		(98)		11,621
Total AFS debt securities	$	1,078,474	$	38,261	$	(922)	$	1,115,813
December 31, 2019
Obligations of states and political subdivisions	$	115,632	$	2,779	$	(328)	$	118,083
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises	462,593		3,398		(2,605)		463,386
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises	325,200		3,183		(2,478)		325,905
Subordinated corporate bonds	10,553		191		—		10,744
Total AFS debt securities	$	913,978	$	9,551	$	(5,411)	$	918,118

Net unrealized gains on AFS debt securities reported within AOCI at December 31, 2020, were $29.3 million, net of a deferred tax liability of $8.0 million. Net unrealized gains on AFS debt securities reported within AOCI at December 31, 2019, were $3.3 million, net of a deferred tax liability of $890,000, respectively.

The following table presents the Company's AFS debt securities with gross unrealized losses, for which an ACL has not been recorded at December 31, 2020, segregated by the length of time the securities have been in a continuous loss position:


		Less Than 12 Months				12 Months or More				Total
(In thousands, except number of holdings)	Number of Holdings	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
December 31, 2020
Obligations of states and political subdivisions	1	$	2,404	$	(115)	$	—	$	—	$	2,404	$	(115)
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises	15	61,222		(568)		980		(6)		62,202		(574)
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises	9	39,107		(135)		—		—		39,107		(135)
Subordinated corporate bonds	5	4,902		(98)		—		—		4,902		(98)
Total AFS debt securities	30	$	107,635	$	(916)	$	980	$	(6)	$	108,615	$	(922)



December 31, 2019
Obligations of states and political subdivisions	11	$	30,459	$	(328)	$	—	$	—	$	30,459	$	(328)
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises	59	162,964		(1,850)		63,633		(755)		226,597		(2,605)
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises	35	66,549		(733)		68,614		(1,745)		135,163		(2,478)

Total AFS debt securities	105	$	259,972	$	(2,911)	$	132,247	$	(2,500)	$	392,219	$	(5,411)

As of December 31, 2020, the unrealized losses on Company's AFS debt securities have not been recognized into income because management does not intend to sell and it is not more-likely-than-not it will be required to sell any of the AFS debt securities before recovery of its amortized cost basis, and the unrealized losses were largely due to changes in interest rates and other market conditions and not reflective of credit events. The issuers continue to make timely principal and interest payments on the bonds.

The amortized cost and estimated fair values of AFS debt securities by contractual maturity at December 31, 2020 are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.


(In thousands)	Amortized Cost		Fair Value
Due in one year or less	$	5,472	$	5,495
Due after one year through five years	59,769		61,338
Due after five years through ten years	248,035		263,889
Due after ten years	765,198		785,091
	$	1,078,474	$	1,115,813

HTM debt securities are reported on the Company's consolidated statements of condition at amortized cost. The following table summarizes the amortized cost, estimated fair value and unrealized gains (losses) of HTM debt securities as of the dates indicated:


(In thousands)	Amortized Cost		Unrealized Gains		Unrealized Losses		Fair Value
December 31, 2020
Obligations of states and political subdivisions	$	1,297	$	114	$	—	$	1,411
Total HTM debt securities	$	1,297	$	114	$	—	$	1,411
December 31, 2019
Obligations of states and political subdivisions	$	1,302	$	57	$	—	$	1,359
Total HTM debt securities	$	1,302	$	57	$	—	$	1,359

As of December 31, 2020, the Company’s HTM debt securities portfolio was made up of three investment grade municipal debt securities, of which two securities also carried credit enhancements. The HTM debt securities portfolio was comprised solely of high credit quality (rated AA or higher) state and municipal obligations. High credit quality state and municipal obligations have a history of zero to near-zero credit loss. As a result, the Company determined that the expected credit loss on its HTM portfolio was immaterial, and therefore, an allowance was not recorded at December 31, 2020.

As of December 31, 2020, none of the Company's HTM debt securities were past due or on non-accrual status. The Company did not recognize any interest income on non-accrual HTM debt securities during the year ended December 31, 2020. At December 31, 2020 and 2019, total accrued interest receivable on HTM debt securities, which has been excluded from reported amortized cost basis on HTM debt securities, was $10,000 and reported within other assets on the consolidated statements of condition. An allowance was not carried on the accrued interest receivable at either date.

The amortized cost and estimated fair values of HTM debt securities by contractual maturity at December 31, 2020 are shown below. Expected maturities will differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.

AFS and HTM Debt securities OTTI. For annual and interim reporting periods prior to October 1, 2020, management reviewed the Company’s AFS and HTM investments quarterly to determine the cause, magnitude and duration of declines in the fair value of each security. Thorough evaluations of the causes of the unrealized losses were performed to determine whether the impairment is temporary or other-than-temporary in nature. Considerations such as the ability of the securities to meet cash flow requirements, levels of credit enhancements, risk of curtailment, and recoverability of invested amount over a reasonable period of time, and the length of time the security was in a loss position, for example, were applied in determining OTTI. Once a decline in value was determined to be other-than-temporary, the cost basis of the security was permanently reduced and a corresponding charge to earnings was recognized.

At December 31, 2019, unrealized losses within the AFS and HTM investment portfolios were reflective of current interest rates in excess of the yield received on debt investments and were not indicative of an overall change in credit quality or other factors. At December 31, 2019, gross unrealized losses on the Company's AFS and HTM debt securities were 1%. At December 31, 2019, the Company had the intent and ability to retain its debt investments that were in an unrealized loss position until the decline in value recovered.

AFS and HTM Debt Securities Pledged. At December 31, 2020 and 2019, AFS and HTM debt securities with an amortized cost of $485.0 million and $709.0 million, respectively, and estimated fair values of $507.1 million and $712.4 million, respectively, were pledged to secure FHLBB advances, public deposits, and securities sold under agreements to repurchase, and for other purposes required or permitted by law.

The following table summarizes the cost and estimated fair values of the Company's investment in equity securities, FHLBB stock and FRBB stock as presented within other investments on the consolidated statements of condition, as of the dates indicated:


(In thousands)	Cost		Unrealized Gains		Unrealized Losses		Fair Value / Carrying Value
December 31, 2020
FHLBB (carried at cost)	$	6,168	$	—	$	—	$	6,168
FRB (carried at cost)	5,374		—		—		5,374
Total other investments	$	11,542	$	—	$	—	$	11,542
December 31, 2019
Equity securities - bank stock (carried at fair value)	$	544	$	1,130	$	—	$	1,674
FHLBB (carried at cost)	6,601		—		—		6,601
FRB (carried at cost)	5,374		—		—		5,374
Total other investments	$	12,519	$	1,130	$	—	$	13,649

During the year ended December 31, 2020, the Company's bank stock equity securities were redeemed by the issuer, as part of a merger agreement, and the Company received proceeds of $1.7 million from the redemption. For the year ended December 31, 2020, the Company realized a gain on its bank stock equity securities of $1.2 million, of which $38,000 was recognized as a realized gain during 2020, $928,000 and $(50,000) were recognized as unrealized gains in 2019 and 2018, respectively. The gains, which were due to the change in fair value of the equity securities, were presented within other income on the consolidated statements of income.