Investment Securities (Tables)

3 Months Ended

Mar. 31, 2024

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 AFS debt securities and the corresponding amounts of unrealized gains and losses recognized in accumulated other comprehensive loss at March 31, 2024 and December 31, 2023:  

	March 31, 2024
	Amortized cost		Gross unrealized gains		Gross unrealized losses		Allowance for credit losses for investments		Fair Value
Investment Securities
AFS debt securities
U.S. government agency securities	$	416,953	$	145	$	(1,171)	$	—	$	415,927
Mortgage-backed securities - residential	984,473		—		(158,259)		—		826,214
Mortgage-backed securities - commercial	17,899		—		(1,284)		—		16,615
Municipal securities	194,470		45		(22,843)		—		171,672
U.S. Treasury securities	30,985		—		(128)		—		30,857
Corporate securities	3,500		—		(103)		—		3,397
Total	$	1,648,280	$	190	$	(183,788)	$	—	$	1,464,682

	December 31, 2023
	Amortized cost		Gross unrealized gains		Gross unrealized losses		Allowance for credit losses for investments		Fair Value
Investment Securities
AFS debt securities
U.S. government agency securities	$	204,663	$	470	$	(1,177)	$	—	$	203,956
Mortgage-backed securities - residential	1,057,389		—		(160,418)		—		896,971
Mortgage-backed securities - commercial	18,186		—		(1,225)		—		16,961
Municipal securities	263,312		370		(21,419)		—		242,263
U.S. Treasury securities	111,729		—		(3,233)		—		108,496
Corporate securities	3,500		—		(174)		—		3,326
Total	$	1,658,779	$	840	$	(187,646)	$	—	$	1,471,973

Schedule of Gross Unrealized Losses

The following tables show gross unrealized losses for which an allowance for credit losses has not been recorded at March 31, 2024 and December 31, 2023, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position:

	March 31, 2024
	Less than 12 months				12 months or more				Total
	Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss
U.S. government agency securities	$	203,870	$	(484)	$	7,251	$	(687)	$	211,121	$	(1,171)
Mortgage-backed securities - residential	—		—		776,208		(158,259)		776,208		(158,259)
Mortgage-backed securities - commercial	—		—		16,615		(1,284)		16,615		(1,284)
Municipal securities	9,131		(41)		155,959		(22,802)		165,090		(22,843)
U.S. Treasury securities	—		—		30,857		(128)		30,857		(128)
Corporate securities	—		—		3,397		(103)		3,397		(103)
Total	$	213,001	$	(525)	$	990,287	$	(183,263)	$	1,203,288	$	(183,788)

	December 31, 2023
	Less than 12 months				12 months or more				Total
	Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss		Fair Value		Gross Unrealized Loss
U.S. government agency securities	$	25,923	$	(21)	$	14,040	$	(1,156)	$	39,963	$	(1,177)
Mortgage-backed securities - residential	—		—		896,971		(160,418)		896,971		(160,418)
Mortgage-backed securities - commercial	—		—		16,961		(1,225)		16,961		(1,225)
Municipal securities	14,480		(148)		188,669		(21,271)		203,149		(21,419)
U.S. Treasury securities	—		—		108,496		(3,233)		108,496		(3,233)
Corporate securities	—		—		3,326		(174)		3,326		(174)
Total	$	40,403	$	(169)	$	1,228,463	$	(187,477)	$	1,268,866	$	(187,646)

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

	March 31,				December 31,
	2024				2023
	Available-for-sale				Available-for-sale
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	34,073	$	33,910	$	64,776	$	64,279
Due in one to five years	10,851		10,080		75,996		71,801
Due in five to ten years	40,939		39,932		51,162		49,630
Due in over ten years	560,045		537,931		391,270		372,331
	645,908		621,853		583,204		558,041
Mortgage-backed securities - residential	984,473		826,214		1,057,389		896,971
Mortgage-backed securities - commercial	17,899		16,615		18,186		16,961
Total AFS debt securities	$	1,648,280	$	1,464,682	$	1,658,779	$	1,471,973

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

Sales and other dispositions of AFS debt securities were as follows:

	Three Months Ended March 31,
	2024		2023
Proceeds from sales	$	207,882	$	—
Proceeds from maturities, prepayments and calls	66,627		26,827
Gross realized gains	90		—
Gross realized losses	16,303		—