Investment Securities (Tables)

12 Months Ended

Dec. 31, 2022

Investment Securities

Schedule of amortized cost and fair value of securities

	2022								2021
	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	$	163,309	$	—	$	(12,327)	$	150,982	$	196,662	$	125	$	(4,224)	$	192,563
Government-sponsored enterprises debt securities		45,000		—		(699)		44,301		—		—		—		—
Mortgage-backed securities:
Residential - Government agency		66,792		—		(7,069)		59,723		135,764		1,791		(291)		137,264
Residential - Government-sponsored enterprises		1,317,718		—		(157,263)		1,160,455		1,496,605		6,914		(12,419)		1,491,100
Commercial - Government agency		282,700		—		(44,847)		237,853		392,443		1,741		(6,521)		387,663
Commercial - Government-sponsored enterprises		130,612		—		(11,039)		119,573		1,415,511		2,646		(48,714)		1,369,443
Commercial - Non-agency		21,964		—		(493)		21,471		—		—		—		—
Collateralized mortgage obligations:
Government agency		738,524		—		(85,202)		653,322		2,103,187		7,768		(31,432)		2,079,523
Government-sponsored enterprises		533,103		—		(70,971)		462,132		2,671,131		3,608		(53,695)		2,621,044
Collateralized loan obligations		249,877		50		(8,606)		241,321		105,245		2		—		105,247
Debt securities issued by states and political subdivisions		—		—		—		—		44,185		—		—		44,185
Total available-for-sale securities	$	3,549,599	$	50	$	(398,516)	$	3,151,133	$	8,560,733	$	24,595	$	(157,296)	$	8,428,032
Government agency debt securities	$	54,318	$	—	$	(5,674)	$	48,644	$	—	$	—	$	—	$	—
Mortgage-backed securities:
Residential - Government agency		46,302		—		(6,294)		40,008		—		—		—		—
Residential - Government-sponsored enterprises		106,534		—		(12,978)		93,556		—		—		—		—
Commercial - Government agency		30,544		—		(5,229)		25,315		—		—		—		—
Commercial - Government-sponsored enterprises		1,150,449		—		(138,451)		1,011,998		—		—		—		—
Collateralized mortgage obligations:
Government agency		1,080,492		—		(122,378)		958,114		—		—		—		—
Government-sponsored enterprises		1,798,178		—		(207,045)		1,591,133		—		—		—		—
Debt securities issued by states and political subdivisions		53,822		—		(7,768)		46,054		—		—		—		—
Total held-to-maturity securities	$	4,320,639	$	—	$	(505,817)	$	3,814,822	$	—	$	—	$	—	$	—

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

	December 31, 2022
	Amortized		Fair
(dollars in thousands)	Cost		Value
Available-for-sale securities
Due in one year or less	$	55,021	$	54,644
Due after one year through five years		80,163		76,492
Due after five years through ten years		180,105		170,568
Due after ten years		164,861		156,371
		480,150		458,075
Mortgage-backed securities:
Residential - Government agency		66,792		59,723
Residential - Government-sponsored enterprises		1,317,718		1,160,455
Commercial - Government agency		282,700		237,853
Commercial - Government-sponsored enterprises		130,612		119,573
Total mortgage-backed securities		1,797,822		1,577,604
Collateralized mortgage obligations:
Government agency		738,524		653,322
Government-sponsored enterprises		533,103		462,132
Total collateralized mortgage obligations		1,271,627		1,115,454
Total available-for-sale securities	$	3,549,599	$	3,151,133
Held-to-maturity securities
Due in one year or less	$	—	$	—
Due after one year through five years		—		—
Due after five years through ten years		10,208		8,932
Due after ten years		97,932		85,766
		108,140		94,698
Mortgage-backed securities:
Residential - Government agency		46,302		40,008
Residential - Government-sponsored enterprises		106,534		93,556
Commercial - Government agency		30,544		25,315
Commercial - Government-sponsored enterprises		1,150,449		1,011,998
Total mortgage-backed securities		1,333,829		1,170,877
Collateralized mortgage obligations:
Government agency		1,080,492		958,114
Government-sponsored enterprises		1,798,178		1,591,133
Total collateralized mortgage obligations		2,878,670		2,549,247
Total held-to-maturity securities	$	4,320,639	$	3,814,822

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

	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

	Time in Continuous Loss as of December 31, 2021
	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	$	(3,355)	$	134,468	$	(869)	$	16,642	$	(4,224)	$	151,110
Mortgage-backed securities:
Residential - Government agency		(291)		51,231		—		—		(291)		51,231
Residential - Government-sponsored enterprises		(10,876)		1,230,104		(1,543)		32,415		(12,419)		1,262,519
Commercial - Government agency		(5,239)		186,024		(1,282)		26,063		(6,521)		212,087
Commercial - Government-sponsored enterprises		(22,179)		744,819		(26,535)		397,123		(48,714)		1,141,942
Collateralized mortgage obligations:
Government agency		(31,432)		1,441,848		—		—		(31,432)		1,441,848
Government-sponsored enterprises		(52,551)		2,255,535		(1,144)		24,959		(53,695)		2,280,494
Total available-for-sale securities with unrealized losses	$	(125,923)	$	6,044,029	$	(31,373)	$	497,202	$	(157,296)	$	6,541,231