Investment securities (Tables)

12 Months Ended

Dec. 31, 2022

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost of Securities and Fair Values

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 (loss) income at December 31, 2022 and 2021:  

	December 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	$	45,167	$	—	$	(5,105)	$	—	$	40,062
Mortgage-backed securities - residential	1,224,522		—		(190,329)		—		1,034,193
Mortgage-backed securities - commercial	19,209		—		(1,565)		—		17,644
Municipal securities	295,375		458		(31,413)		—		264,420
U.S. Treasury securities	113,301		—		(5,621)		—		107,680
Corporate securities	8,000		—		(813)		—		7,187
Total	$	1,705,574	$	458	$	(234,846)	$	—	$	1,471,186

	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

Schedule of Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

Therefore, mortgage-backed securities are not included in the maturity categories in the following summary.

	December 31,
	2022				2021
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	4,277	$	4,225	$	21,851	$	21,884
Due in one to five years	161,556		152,181		54,847		55,307
Due in five to ten years	61,290		57,859		45,714		46,975
Due in over ten years	234,720		205,084		255,077		269,737
	461,843		419,349		377,489		393,903
Mortgage-backed securities - residential	1,224,522		1,034,193		1,281,285		1,269,372
Mortgage-backed securities - commercial	19,209		17,644		15,024		15,250
Total debt securities	$	1,705,574	$	1,471,186	$	1,673,798	$	1,678,525

Schedule of Sales and Other Dispositions of Available-for-Sale Securities

Sales and other dispositions of available-for-sale securities were as follows:

	Years Ended December 31,
	2022		2021		2020
Proceeds from sales	$	1,218	$	8,855	$	146,494
Proceeds from maturities, prepayments and calls	204,748		296,256		220,549
Gross realized gains	4		127		1,606
Gross realized losses	3		1		271

Schedule of Gross Unrealized Losses

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

	December 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	$	23,791	$	(2,802)	$	16,271	$	(2,303)	$	40,062	$	(5,105)
Mortgage-backed securities - residential	316,656		(32,470)		717,533		(157,859)		1,034,189		(190,329)
Mortgage-backed securities - commercial	11,104		(968)		6,541		(597)		17,645		(1,565)
Municipal securities	196,419		(26,811)		36,726		(4,602)		233,145		(31,413)
U.S. Treasury securities	94,248		(4,122)		13,434		(1,499)		107,682		(5,621)
Corporate securities	4,008		(492)		3,270		(321)		7,278		(813)
Total	$	646,226	$	(67,665)	$	793,775	$	(167,181)	$	1,440,001	$	(234,846)

	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)