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 March 31, 2022 and December 31, 2021:


	March 31, 2022
	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	$	41,015	$	—	$	(2,133)	$	—	$	38,882
Mortgage-backed securities - residential	1,320,205		616		(88,565)		—		1,232,256
Mortgage-backed securities - commercial	14,738		14		(445)		—		14,307
Municipal securities	318,587		3,594		(12,043)		—		310,138
U.S. Treasury securities	81,913		4		(1,744)		—		80,173
Corporate securities	8,000		4		(235)		—		7,769
Total	$	1,784,458	$	4,232	$	(105,165)	$	—	$	1,683,525


	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

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 March 31, 2022 and December 31, 2021, total accrued interest receivable on debt securities was $5,331 and $5,051, respectively.

As of March 31, 2022 and December 31, 2021, the Company had $3,213 and $3,367, in marketable equity securities recorded at fair value, respectively.

Securities pledged at March 31, 2022 and December 31, 2021 had carrying amounts of $1,253,407 and $1,226,646, 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 March 31, 2022 and December 31, 2021, 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 March 31, 2022 and December 31, 2021 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 summary.


	March 31,				December 31,
	2022				2021
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	19,614	$	19,602	$	21,851	$	21,884
Due in one to five years	121,436		118,438		54,847		55,307
Due in five to ten years	55,733		54,635		45,714		46,975
Due in over ten years	252,732		244,287		255,077		269,737
	449,515		436,962		377,489		393,903
Mortgage-backed securities - residential	1,320,205		1,232,256		1,281,285		1,269,372
Mortgage-backed securities - commercial	14,738		14,307		15,024		15,250
Total debt securities	$	1,784,458	$	1,683,525	$	1,673,798	$	1,678,525


	Three Months Ended March 31,
		2022		2021
Proceeds from sales		$	—	$	—
Proceeds from maturities, prepayments and calls		57,443		61,040
Gross realized gains		2		7
Gross realized losses		—		—

Additionally, the change in the fair value of equity securities and sale of equity securities resulted in a net loss of $154 and a net gain of $76 for the three months ended March 31, 2022 and 2021, respectively.

The following tables show gross unrealized losses for which an allowance for credit losses has not been recorded at March 31, 2022 and December 31, 2021, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:


	March 31, 2022
	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	$	38,882	$	(2,133)	$	—	$	—	$	38,882	$	(2,133)
Mortgage-backed securities - residential	961,993		(70,839)		175,988		(17,726)		1,137,981		(88,565)
Mortgage-backed securities - commercial	9,647		(445)		—		—		9,647		(445)
Municipal securities	192,546		(11,844)		1,030		(199)		193,576		(12,043)
U.S. Treasury securities	47,918		(1,744)		—		—		47,918		(1,744)
Corporate securities	6,896		(235)		—		—		6,896		(235)
Total	$	1,257,882	$	(87,240)	$	177,018	$	(17,925)	$	1,434,900	$	(105,165)


	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)

As of March 31, 2022 and December 31, 2021, the Company’s securities portfolio consisted of 514 and 511 securities, 321 and 80 of which were in an unrealized loss position, respectively.