Securities (Tables)

12 Months Ended

Dec. 31, 2022

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities Available for Sale

Securities Available for Sale
	December 31,2022								December 31,2021
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
($ in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency    securities	$	113,211	$	—	$	2,346	$	110,865	$	420,857	$	3,781	$	5,340	$	419,298
Municipal obligations		207,014		59		3,981		203,092		304,536		13,184		3,562		314,158
Residential mortgage-backed securities		2,655,381		224		398,619		2,256,986		3,056,763		29,158		50,123		3,035,798
Commercial mortgage-backed securities		3,234,278		2,032		342,880		2,893,430		3,064,828		61,645		48,614		3,077,859
Collateralized mortgage obligations		76,830		—		6,242		70,588		119,046		1,837		—		120,883
Corporate debt securities		23,500		—		2,420		21,080		18,500		210		8		18,702
	$	6,310,214	$	2,315	$	756,488	$	5,556,041	$	6,984,530	$	109,815	$	107,647	$	6,986,698

Amortized Cost and Fair Value of Debt Securities Held to Maturity

Securities Held to Maturity
	December 31,2022								December 31,2021
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
($ in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency    securities	$	426,454	$	21	$	49,044	$	377,431	$	14,857	$	—	$	20	$	14,837
Municipal obligations		698,908		753		26,558		673,103		621,405		37,941		205		659,141
Residential mortgage-backed securities		734,478		—		72,532		661,946		268,907		682		1,499		268,090
Commercial mortgage-backed securities		948,691		—		87,211		861,480		603,156		28,679		669		631,166
Collateralized mortgage obligations		43,964		—		2,526		41,438		57,426		822		—		58,248
	$	2,852,495	$	774	$	237,871	$	2,615,398	$	1,565,751	$	68,124	$	2,393	$	1,631,482

Proceeds from Gross Gains on and Gross Losses on Sale of Securities

The following table presents the proceeds from, gross gains on, and gross losses on sales of securities during the years ended December 31, 2022, 2021 and 2020. Net gains or losses are reflected in the "Securities transactions" line item on the Consolidated Statements of Income.

	Years Ended December 31,
($ in thousands)	2022		2021		2020
Proceeds	$	73,219	$	198,681	$	211,919
Gross gains		—		1,649		1,984
Gross losses		87		1,316		1,496

Available for Sale Securities [Member]

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

($ in thousands)	Amortized Cost		Fair Value
Debt Securities Available for Sale
Due in one year or less	$	112	$	111
Due after one year through five years		919,639		871,760
Due after five years through ten years		2,982,549		2,665,232
Due after ten years		2,407,914		2,018,938
Total available for sale debt securities	$	6,310,214	$	5,556,041

Securities with Unrealized Losses

Available for sale
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
($ in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	102,607	$	754	$	8,258	$	1,592	$	110,865	$	2,346
Municipal obligations		192,334		3,981		—		—		192,334		3,981
Residential mortgage-backed securities		636,060		49,790		1,611,832		348,829		2,247,892		398,619
Commercial mortgage-backed securities		1,489,974		114,195		1,351,530		228,685		2,841,504		342,880
Collateralized mortgage obligations		41,703		3,275		28,884		2,967		70,587		6,242
Corporate debt securities		13,194		1,306		7,386		1,114		20,580		2,420
.	$	2,475,872	$	173,301	$	3,007,890	$	583,187	$	5,483,762	$	756,488

Available for sale
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
($ in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	198,318	$	2,305	$	63,534	$	3,035	$	261,852	$	5,340
Municipal obligations		43,021		2,372		25,126		1,190		68,147		3,562
Residential mortgage-backed securities		1,293,179		20,581		819,596		29,541		2,112,775		50,122
Commercial mortgage-backed securities		786,206		14,819		665,687		33,796		1,451,893		48,615
Collateralized mortgage obligations		—		—		—		—		—		—
Corporate debt securities		6,992		8		—		—		6,992		8
	$	2,327,716	$	40,085	$	1,573,943	$	67,562	$	3,901,659	$	107,647

Held-to-maturity Securities [Member]

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

($ in thousands)	Amortized Cost		Fair Value
Debt Securities Held to Maturity
Due in one year or less	$	10,000	$	9,924
Due after one year through five years		544,146		522,347
Due after five years through ten years		893,562		813,726
Due after ten years		1,404,787		1,269,401
Total held to maturity debt securities	$	2,852,495	$	2,615,398

Securities with Unrealized Losses

Held to maturity
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
($ in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	145,893	$	13,245	$	226,499	$	35,799	$	372,392	$	49,044
Municipal obligations		560,288		8,878		64,346		17,680		624,634		26,558
Residential mortgage-backed securities		391,146		30,515		270,800		42,017		661,946		72,532
Commercial mortgage-backed securities		697,827		56,899		163,653		30,312		861,480		87,211
Collateralized mortgage obligations		41,438		2,526		—		—		41,438		2,526
	$	1,836,592	$	112,063	$	725,298	$	125,808	$	2,561,890	$	237,871

Held to maturity
	Losses < 12 Months				Losses 12 Months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
($ in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	14,837	$	20	$	—	$	—	$	14,837	$	20
Municipal obligations		7,795		205		—		—		7,795		205
Residential mortgage-backed securities		253,661		1,499		—		—		253,661		1,499
Commercial mortgage-backed securities		56,366		205		11,837		464		68,203		669
Collateralized mortgage obligations		—		—		—		—		—		—
	$	332,659	$	1,929	$	11,837	$	464	$	344,496	$	2,393