Investment securities (Tables)

6 Months Ended

Jun. 30, 2023

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 at June 30, 2023 and December 31, 2022:  

	June 30, 2023
	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	$	45,185	$	—	$	(4,656)	$	—	$	40,529
Mortgage-backed securities - residential	1,165,901		—		(186,501)		—		979,400
Mortgage-backed securities - commercial	18,747		—		(1,493)		—		17,254
Municipal securities	294,032		387		(27,322)		—		267,097
U.S. Treasury securities	113,508		—		(5,287)		—		108,221
Corporate securities	8,000		—		(1,141)		—		6,859
Total	$	1,645,373	$	387	$	(226,400)	$	—	$	1,419,360

	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

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.

	June 30,				December 31,
	2023				2022
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	66,285	$	64,880	$	4,277	$	4,225
Due in one to five years	106,548		98,449		161,556		152,181
Due in five to ten years	60,725		57,675		61,290		57,859
Due in over ten years	227,167		201,702		234,720		205,084
	460,725		422,706		461,843		419,349
Mortgage-backed securities - residential	1,165,901		979,400		1,224,522		1,034,193
Mortgage-backed securities - commercial	18,747		17,254		19,209		17,644
Total debt securities	$	1,645,373	$	1,419,360	$	1,705,574	$	1,471,186

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

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

	Three Months Ended June 30,				Six Months Ended June 30,
	2023		2022		2023		2022
Proceeds from sales	$	—	$	1,218	$	—	$	1,218
Proceeds from maturities, prepayments and calls	31,588		68,906		58,415		126,349
Gross realized gains	—		1		—		3
Gross realized losses	—		—		—		—

Schedule of Gross Unrealized Losses

The following tables show gross unrealized losses for which an allowance for credit losses has not been recorded at June 30, 2023 and December 31, 2022, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

	June 30, 2023
	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	$	956	$	(11)	$	39,573	$	(4,645)	$	40,529	$	(4,656)
Mortgage-backed securities - residential	43,118		(2,190)		936,282		(184,311)		979,400		(186,501)
Mortgage-backed securities - commercial	—		—		17,254		(1,493)		17,254		(1,493)
Municipal securities	53,700		(767)		179,210		(26,555)		232,910		(27,322)
U.S. Treasury securities	249		(1)		107,972		(5,286)		108,221		(5,287)
Corporate securities	—		—		6,859		(1,141)		6,859		(1,141)
Total	$	98,023	$	(2,969)	$	1,287,150	$	(223,431)	$	1,385,173	$	(226,400)

	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)		717,537		(157,859)		1,034,193		(190,329)
Mortgage-backed securities - commercial	11,104		(968)		6,540		(597)		17,644		(1,565)
Municipal securities	196,419		(26,811)		36,726		(4,602)		233,145		(31,413)
U.S. Treasury securities	94,248		(4,122)		13,432		(1,499)		107,680		(5,621)
Corporate securities	4,008		(492)		3,179		(321)		7,187		(813)
Total	$	646,226	$	(67,665)	$	793,685	$	(167,181)	$	1,439,911	$	(234,846)