Investment Securities (Tables)

12 Months Ended

Dec. 31, 2023

Investment Securities

Schedule of amortized cost and fair value of securities

	2023								2022
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(dollars in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency debt securities	$	33,169	$	—	$	(666)	$	32,503	$	163,309	$	—	$	(12,327)	$	150,982
Government-sponsored enterprises debt securities		20,000		—		(408)		19,592		45,000		—		(699)		44,301
Mortgage-backed securities:
Residential - Government agency		11,303		—		(1,121)		10,182		66,792		—		(7,069)		59,723
Residential - Government-sponsored enterprises		895,421		—		(112,124)		783,297		1,317,718		—		(157,263)		1,160,455
Commercial - Government agency		268,944		—		(50,270)		218,674		282,700		—		(44,847)		237,853
Commercial - Government-sponsored enterprises		93,459		—		(7,028)		86,431		130,612		—		(11,039)		119,573
Commercial - Non-agency		21,964		—		(281)		21,683		21,964		—		(493)		21,471
Collateralized mortgage obligations:
Government agency		538,718		—		(67,568)		471,150		738,524		—		(85,202)		653,322
Government-sponsored enterprises		425,826		—		(61,856)		363,970		533,103		—		(70,971)		462,132
Collateralized loan obligations		249,871		43		(2,060)		247,854		249,877		50		(8,606)		241,321
Total available-for-sale securities	$	2,558,675	$	43	$	(303,382)	$	2,255,336	$	3,549,599	$	50	$	(398,516)	$	3,151,133
Government agency debt securities	$	52,051	$	—	$	(4,497)	$	47,554	$	54,318	$	—	$	(5,674)	$	48,644
Mortgage-backed securities:
Residential - Government agency		43,885		—		(5,189)		38,696		46,302		—		(6,294)		40,008
Residential - Government-sponsored enterprises		99,379		—		(11,013)		88,366		106,534		—		(12,978)		93,556
Commercial - Government agency		30,795		—		(7,017)		23,778		30,544		—		(5,229)		25,315
Commercial - Government-sponsored enterprises		1,129,738		195		(130,757)		999,176		1,150,449		—		(138,451)		1,011,998
Collateralized mortgage obligations:
Government agency		989,130		—		(109,471)		879,659		1,080,492		—		(122,378)		958,114
Government-sponsored enterprises		1,642,274		—		(193,897)		1,448,377		1,798,178		—		(207,045)		1,591,133
Debt securities issued by states and political subdivisions		54,197		—		(4,947)		49,250		53,822		—		(7,768)		46,054
Total held-to-maturity securities	$	4,041,449	$	195	$	(466,788)	$	3,574,856	$	4,320,639	$	—	$	(505,817)	$	3,814,822

Schedule of amortized cost and fair value of debt securities by contractual maturity

	December 31, 2023
	Amortized		Fair
(dollars in thousands)	Cost		Value
Available-for-sale securities
Due in one year or less	$	25,071	$	24,742
Due after one year through five years		37,373		36,527
Due after five years through ten years		97,695		96,879
Due after ten years		164,865		163,484
		325,004		321,632
Mortgage-backed securities:
Residential - Government agency		11,303		10,182
Residential - Government-sponsored enterprises		895,421		783,297
Commercial - Government agency		268,944		218,674
Commercial - Government-sponsored enterprises		93,459		86,431
Total mortgage-backed securities		1,269,127		1,098,584
Collateralized mortgage obligations:
Government agency		538,718		471,150
Government-sponsored enterprises		425,826		363,970
Total collateralized mortgage obligations		964,544		835,120
Total available-for-sale securities	$	2,558,675	$	2,255,336
Held-to-maturity securities
Due in one year or less	$	—	$	—
Due after one year through five years		—		—
Due after five years through ten years		22,082		20,318
Due after ten years		84,166		76,486
		106,248		96,804
Mortgage-backed securities:
Residential - Government agency		43,885		38,696
Residential - Government-sponsored enterprises		99,379		88,366
Commercial - Government agency		30,795		23,778
Commercial - Government-sponsored enterprises		1,129,738		999,176
Total mortgage-backed securities		1,303,797		1,150,016
Collateralized mortgage obligations:
Government agency		989,130		879,659
Government-sponsored enterprises		1,642,274		1,448,377
Total collateralized mortgage obligations		2,631,404		2,328,036
Total held-to-maturity securities	$	4,041,449	$	3,574,856

Schedule of gross unrealized losses and fair values of securities in a continuous loss position

	Time in Continuous Loss as of December 31, 2023
	Less Than 12 Months				12 Months or More				Total
	Unrealized				Unrealized				Unrealized
(dollars in thousands)	Losses		Fair Value		Losses		Fair Value		Losses		Fair Value
U.S. Treasury and government agency debt securities	$	—	$	—	$	(666)	$	32,503	$	(666)	$	32,503
Government-sponsored enterprises debt securities		—		—		(408)		19,592		(408)		19,592
Mortgage-backed securities:
Residential - Government agency		—		—		(1,121)		10,182		(1,121)		10,182
Residential - Government-sponsored enterprises		—		—		(112,124)		783,297		(112,124)		783,297
Commercial - Government agency		—		—		(50,270)		218,674		(50,270)		218,674
Commercial - Government-sponsored enterprises		—		—		(7,028)		86,431		(7,028)		86,431
Commercial - Non-agency		—		—		(281)		21,683		(281)		21,683
Collateralized mortgage obligations:
Government agency		—		—		(67,568)		471,150		(67,568)		471,150
Government-sponsored enterprises		—		—		(61,856)		363,970		(61,856)		363,970
Collateralized loan obligations		(564)		63,667		(1,496)		163,126		(2,060)		226,793
Total available-for-sale securities with unrealized losses	$	(564)	$	63,667	$	(302,818)	$	2,170,608	$	(303,382)	$	2,234,275

	Time in Continuous Loss as of December 31, 2022
	Less Than 12 Months				12 Months or More				Total
	Unrealized				Unrealized				Unrealized
(dollars in thousands)	Losses		Fair Value		Losses		Fair Value		Losses		Fair Value
U.S. Treasury and government agency debt securities	$	(2,962)	$	83,870	$	(9,365)	$	67,112	$	(12,327)	$	150,982
Government-sponsored enterprises debt securities		(699)		44,301		—		—		(699)		44,301
Mortgage-backed securities:
Residential - Government agency		(7,069)		59,723		—		—		(7,069)		59,723
Residential - Government-sponsored enterprises		(73,954)		645,338		(83,309)		515,117		(157,263)		1,160,455
Commercial - Government agency		(15,852)		108,842		(28,995)		129,011		(44,847)		237,853
Commercial - Government-sponsored enterprises		(7,348)		94,657		(3,691)		24,916		(11,039)		119,573
Commercial - Non-agency		(493)		21,471		—		—		(493)		21,471
Collateralized mortgage obligations:
Government agency		(74,797)		596,907		(10,405)		56,415		(85,202)		653,322
Government-sponsored enterprises		(21,916)		198,108		(49,055)		264,024		(70,971)		462,132
Collateralized loan obligations		(8,606)		170,042		—		—		(8,606)		170,042
Total available-for-sale securities with unrealized losses	$	(213,696)	$	2,023,259	$	(184,820)	$	1,056,595	$	(398,516)	$	3,079,854