Securities (Tables)

12 Months Ended

Dec. 31, 2021

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost and Estimated Fair Values of Debt Securities Held for Investment

The following table summarizes the amortized cost and estimated fair values of debt securities held for investment:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(Dollars in thousands)
December 31, 2021
Mortgage backed securities (1)	$	32	$	1	$	—		$	33
States and political subdivisions		2,445		—		—			2,445
Other securities		500		—		—			500
Total	$	2,977	$	1	$	—		$	2,978
December 31, 2020
Mortgage backed securities (1)	$	59	$	3	$	—		$	62
States and political subdivisions		2,405		18		(1	)		2,422
Other securities		500		—		—			500
Total	$	2,964	$	21	$	(1	)	$	2,984

Summary of Amortized Cost and Estimated Fair Values of Debt Securities Available for Sale

The following table summarizes the amortized cost and estimated fair values of debt securities available for sale:

	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(Dollars in thousands)
December 31, 2021
U.S. treasuries	$	455,701	$	3,693	$	(1,766	)	$	457,628
U.S. federal agencies		21,609		335		(2	)		21,942
Mortgage backed securities (1)		28,897		400		(14	)		29,283
States and political subdivisions		6,128		194		(3	)		6,319
Asset backed securities		13,354		3		—			13,357
Other securities		3,000		—		(6	)		2,994
Total	$	528,689	$	4,625	$	(1,791	)	$	531,523
December 31, 2020
U.S. treasuries	$	465,416	$	9,820	$	—		$	475,236
U.S. federal agencies		19,697		1		(60	)		19,638
Mortgage backed securities (1)		15,268		428		—			15,696
States and political subdivisions		28,571		377		—			28,948
Asset backed securities		13,337		—		(623	)		12,714
Total	$	542,289	$	10,626	$	(683	)	$	552,232

(1)Primarily consists of FHLMC, FNMA, GNMA and mortgage backed securities through U.S. agencies.

Maturity of Debt Securities

The maturities of debt securities held for investment and available for sale are summarized in the following table using contractual maturities. Actual maturities may differ from contractual maturities due to obligations that are called or prepaid. For purposes of the maturity table, mortgage-backed securities, which are not due at a single maturity date, have been presented at their contractual maturity.

	December 31,
	2021				2020
	Amortized Cost		Estimated Fair Value		Amortized Cost		Estimated Fair Value
	(Dollars in thousands)
Held for Investment
Contractual maturity of debt securities:
Within one year	$	577	$	577	$	807	$	809
After one year but within five years		2,396		2,397		2,091		2,110
After five years but within ten years		4		4		65		64
After ten years		—		—		1		1
Total	$	2,977	$	2,978	$	2,964	$	2,984
Available for Sale
Contractual maturity of debt securities:
Within one year	$	58,478	$	58,688	$	339,752	$	341,102
After one year but within five years		408,253		410,049		162,401		171,135
After five years but within ten years		10,851		11,011		3,753		3,910
After ten years		51,107		51,775		36,383		36,085
Total debt securities	$	528,689	$	531,523	$	542,289	$	552,232

Company's Book Value of Pledged Debt Securities

The following table is a summary of the Company’s book value of debt securities that were pledged as collateral for public funds on deposit, repurchase agreements and for other purposes as required or permitted by law:

	December 31,
	2021		2020
	(Dollars in thousands)
Book value of pledged securities	$	473,026	$	490,833

Summary of Debt Securities with Unrealized Losses, Segregated by Duration of Unrealized Loss

The following table summarizes debt securities with unrealized losses, segregated by the duration of the unrealized loss, at December 31, 2021 and 2020 respectively:

	Less than 12 Months				More than 12 Months				Total
	Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses		Estimated Fair Value		Unrealized Losses
	(Dollars in thousands)
December 31, 2021
Available for Sale
U.S. treasuries	$	298,080	$	1,766	$	—	$	—	$	298,080	$	1,766
U.S. federal agencies		376		2		—		—		376		2
Mortgage backed securities		2,824		14		—		—		2,824		14
States and political subdivisions		505		3		—		—		505		3
Other securities		2,994		6		—		—		2,994		6
Total	$	304,779	$	1,791	$	—	$	—	$	304,779	$	1,791
December 31, 2020
Held for Investment
States and political subdivisions	$	119	$	1	$	—	$	—	$	119	$	1
Total	$	119	$	1	$	—	$	—	$	119	$	1
Available for Sale
U.S. federal agencies	$	12,236	$	41	$	2,184	$	19	$	14,420	$	60
Asset backed securities		—		—		12,714		623		12,714		623
Total	$	12,236	$	41	$	14,898	$	642	$	27,134	$	683