The following tables summarize the amortized cost, allowance for credit losses and fair value of the available-for-sale debt securities and the corresponding amounts of unrealized gains and losses recognized in accumulated other comprehensive income at December 31, 2021 and 2020:


	December 31, 2021
	Amortized cost		Gross unrealized gains		Gross unrealized losses		Allowance for credit losses for investments		Fair Value
Investment Securities
Available-for-sale debt securities
U.S. government agency securities	$	34,023	$	18	$	(171)	$	—	$	33,870
Mortgage-backed securities - residential	1,281,285		6,072		(17,985)		—		1,269,372
Mortgage-backed securities - commercial	15,024		272		(46)		—		15,250
Municipal securities	322,052		16,718		(160)		—		338,610
U.S. Treasury securities	14,914		—		(6)		—		14,908
Corporate securities	6,500		40		(25)		—		6,515
Total	$	1,673,798	$	23,120	$	(18,393)	$	—	$	1,678,525


	December 31, 2020
	Amortized cost		Gross unrealized gains		Gross unrealized losses		Allowance for credit losses for investments		Fair Value
Investment Securities
Available-for-sale debt securities
U.S. government agency securities	$	2,000	$	3	$	—	$	—	$	2,003
Mortgage-backed securities - residential	760,099		14,040		(803)		—		773,336
Mortgage-backed securities - commercial	20,226		1,362		—		—		21,588
Municipal securities	336,543		19,806		(20)		—		356,329
U.S. Treasury securities	16,480		148		—		—		16,628
Corporate securities	2,500		17		(1)		—		2,516
Total	$	1,137,848	$	35,376	$	(824)	$	—	$	1,172,400

The components of amortized cost for debt securities on the consolidated balance sheets excludes accrued interest receivable since the Company elected to present accrued interest receivable separately on the consolidated balance sheets. As of December 31, 2021 and 2020, total accrued interest receivable on debt securities was $5,051 and $4,540, respectively.

As of December 31, 2021 and 2020, the Company had $3,367 and $4,591, in marketable equity securities recorded at fair value, respectively.

Securities pledged at December 31, 2021 and 2020 had carrying amounts of $1,226,646 and $804,821, respectively, and were pledged to secure a Federal Reserve Bank line of credit, public deposits and repurchase agreements.

There were no holdings of securities of any one issuer, other than U.S. Government sponsored enterprises, in an amount greater than 10% of shareholders' equity during any period presented.

Investment Securities transactions are recorded as of the trade date. At December 31, 2021 and 2020, there were no trade date receivables or payables that related to sales or purchases settled after period end.

The amortized cost and fair value of debt securities by contractual maturity at December 31, 2021 and 2020 are shown below. Maturities may differ from contractual maturities in mortgage-backed securities because the mortgage underlying the security may be called or repaid without any penalties. Therefore, mortgage-backed securities are not included in the maturity categories in the following maturity summary.


	December 31,
	2021				2020
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	21,851	$	21,884	$	35,486	$	35,662
Due in one to five years	54,847		55,307		24,278		24,684
Due in five to ten years	45,714		46,975		40,038		41,332
Due in over ten years	255,077		269,737		257,721		275,798
	377,489		393,903		357,523		377,476
Mortgage-backed securities - residential	1,281,285		1,269,372		760,099		773,336
Mortgage-backed securities - commercial	15,024		15,250		20,226		21,588
Total debt securities	$	1,673,798	$	1,678,525	$	1,137,848	$	1,172,400


	Year Ended December 31,
		2021		2020		2019
Proceeds from sales		$	8,855	$	146,494	$	24,498
Proceeds from maturities, prepayments and calls		296,256		220,549		113,018
Gross realized gains		127		1,606		7
Gross realized losses		1		271		98

Additionally, the change in the fair value of equity securities and gain on sale of equity securities resulted in net gains of $198, $296 and $148 for the years ended December 31, 2021, 2020, and 2019, respectively.

The following tables show gross unrealized losses for which an allowance for credit losses has not been recorded at December 31, 2021 and 2020, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:


	December 31, 2021
	Less than 12 months				12 months or more				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized Loss
U.S. government agency securities	$	18,360	$	(171)	$	—	$	—	$	18,360	$	(171)
Mortgage-backed securities - residential	871,368		(14,295)		102,799		(3,690)		974,167		(17,985)
Mortgage-backed securities - commercial	7,946		(46)		—		—		7,946		(46)
Municipal securities	11,414		(160)		—		—		11,414		(160)
U.S. Treasury securities	14,908		(6)		—		—		14,908		(6)
Corporate securities	4,119		(25)		—		—		4,119		(25)
Total	$	928,115	$	(14,703)	$	102,799	$	(3,690)	$	1,030,914	$	(18,393)


	December 31, 2020
	Less than 12 months				12 months or more				Total
	Fair Value		Unrealized Loss		Fair Value		Unrealized Loss		Fair Value		Unrealized loss

Mortgage-backed securities - residential	$	182,012	$	(803)	$	—	$	—	$	182,012	$	(803)
Municipal securities	3,184		(20)		—		—		3,184		(20)
Corporate Securities	499		(1)		—		—		499		(1)

Total	$	185,695	$	(824)	$	—	$	—	$	185,695	$	(824)

As of December 31, 2021 and 2020, the Company’s securities portfolio consisted of 511 and 514 securities, 80 and 16 of which were in an unrealized loss position, respectively.

As of December 31, 2021 and 2020, the Company evaluated available-for-sale debt securities with unrealized losses for expected credit loss and recorded no allowance for credit loss as the majority of the investment portfolio was either government guaranteed or an issuance of a government sponsored entity, was highly rated by major credit rating agencies and have a long history of zero losses. As such, no provision for credit losses was recorded for the years ended December 31, 2021 and 2020.