Segment Reporting (Details) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Jun. 30, 2025 USD ($) branch	Jun. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	$ 300,000		$ 256,593		$ 585,940	$ 514,451
Noninterest Income	66,977		65,159		125,754	130,144
Provision for Loan, Lease, and Other Losses	17,996		23,008		30,999	47,009
Noninterest Expense	209,352		195,861		419,971	393,518
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	139,629		102,884		260,724	204,068
Income Tax Expense (Benefit)	28,399		(12,689)		47,808	7,326
Net Income (Loss) Attributable to Parent, Total	111,230	$ 101,687	115,573	$ 81,169	212,916	196,742
Goodwill	1,104,992				$ 1,104,992		$ 1,104,992
Number of Reportable Segments | branch					3
Interest Income (Expense), after Provision for Loan Loss	282,004		233,585		$ 554,941	467,442
Labor and Related Expense	126,994		121,581		250,890	240,976
Information Technology and Data Processing	26,508		27,161		53,646	53,362
Occupancy, Net	12,644		13,128		28,025	26,761
Marketing and Advertising Expense	7,748		7,535		14,134	14,052
Equipment Expense	4,494		4,450		9,021	9,049
Professional Fees	6,674		4,429		12,757	9,101
Federal Deposit Insurance Corporation Premium Expense	9,708		7,131		20,144	21,077
Amortization of Intangible Assets	2,203		2,203		4,405	4,405
Other Noninterest Expense	9,674		6,450		21,648	10,963
Commercial and business lending	30,607,605				30,607,605		29,768,586
Assets	43,993,729				43,993,729		$ 43,023,068
Gain (Loss) on Sale of Mortgage Loans	0		0		(6,976)	0
Corporate and Commercial Specialty [Member]
Segment Income Statement Data Abstract
A portion of total depreciation Technology expense	100		100		100	200
Community, Consumer and Business [Member]
Segment Income Statement Data Abstract
A portion of total depreciation Occupancy expense	2,700		2,300		5,300	9,700
Risk Management and Shared Services [Member]
Segment Income Statement Data Abstract
A portion of total depreciation Equipment expense	9,300		9,900		20,500	39,100
Operating Segments
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	300,000		256,593		585,940	514,451
Net intersegment interest income (expense)	0		0		0	0
Segment net interest income	300,000		256,593		585,940	514,451
Noninterest Income	66,977		65,159		125,754	130,144
Provision for Loan, Lease, and Other Losses	17,996		23,008		30,999	47,009
Noninterest Expense	209,352		195,861		419,971	393,518
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	139,629		102,884		260,724	204,068
Income Tax Expense (Benefit)	28,399		(12,689)		47,808	7,326
Net Income (Loss) Attributable to Parent, Total	111,230		115,573		212,916	196,742
Goodwill	1,104,992		1,104,992		1,104,992	1,104,992
Interest Income (Expense), before Provision	366,977		321,752		711,694	644,595
Interest Income (Expense), after Provision for Loan Loss	348,981		298,745		680,695	597,586
Labor and Related Expense	126,994		121,581		250,890	240,976
Information Technology and Data Processing	26,508		27,161		53,646	53,362
Occupancy, Net	12,644		13,128		28,025	26,761
Marketing and Advertising Expense	7,748		7,535		14,134	14,052
Equipment Expense	4,494		4,450		9,021	9,049
Professional Fees	6,674		4,429		12,757	9,101
Payments of Financing Costs	2,705		1,793		5,299	3,771
Federal Deposit Insurance Corporation Premium Expense	9,708		7,131		20,144	21,077
Amortization of Intangible Assets	2,203		2,203		4,405	4,405
Other Noninterest Expense	9,674		6,450		21,648	10,963
Allocated indirect expense	0		0		0	0
Commercial and business lending	30,607,605		29,618,271		30,607,605	29,618,271
Assets	43,993,729		41,623,908		43,993,729	41,623,908
Operating Segments | Corporate and Commercial Specialty [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	242,978		245,797		470,263	485,526
Net intersegment interest income (expense)	(104,430)		(110,719)		(197,772)	(218,284)
Segment net interest income	138,548		135,078		272,491	267,242
Noninterest Income	11,984		11,671		24,887	23,540
Provision for Loan, Lease, and Other Losses	20,368		16,038		39,382	31,036
Noninterest Expense	45,802		43,035		90,954	85,813
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	84,362		87,676		167,042	173,933
Income Tax Expense (Benefit)	15,968		14,084		31,665	31,893
Net Income (Loss) Attributable to Parent, Total	68,394		73,592		135,377	142,040
Goodwill	525,836		525,836		525,836	525,836
Interest Income (Expense), before Provision	150,532		146,749		297,378	290,782
Interest Income (Expense), after Provision for Loan Loss	130,164		130,711		257,996	259,746
Labor and Related Expense	20,149		20,447		41,475	40,877
Information Technology and Data Processing	842		586		1,432	1,187
Occupancy, Net	33		0		33	0
Marketing and Advertising Expense	1,252		823		2,186	1,760
Equipment Expense	0		0		0	1
Professional Fees	220		289		422	424
Payments of Financing Costs	260		113		1,071	359
Federal Deposit Insurance Corporation Premium Expense	0		0		0	0
Amortization of Intangible Assets	0		0		0	0
Other Noninterest Expense	934		841		1,715	1,604
Allocated indirect expense	22,112		19,936		42,620	39,601
Commercial and business lending	17,617,892		16,191,823		17,617,892	16,191,823
Assets	18,431,586		16,817,587		18,431,586	16,817,587
Operating Segments | Community, Consumer and Business [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	68,871		63,207		131,367	124,602
Net intersegment interest income (expense)	133,665		146,814		269,320	290,801
Segment net interest income	202,536		210,021		400,687	415,403
Noninterest Income	51,461		48,878		100,561	95,926
Provision for Loan, Lease, and Other Losses	6,363		6,045		12,434	13,301
Noninterest Expense	134,554		129,924		271,369	263,986
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	113,080		122,930		217,445	234,042
Income Tax Expense (Benefit)	23,747		25,815		45,663	49,149
Net Income (Loss) Attributable to Parent, Total	89,333		97,115		171,782	184,893
Goodwill	579,156		579,156		579,156	579,156
Interest Income (Expense), before Provision	253,997		258,899		501,248	511,329
Interest Income (Expense), after Provision for Loan Loss	247,634		252,854		488,814	498,028
Labor and Related Expense	56,641		56,159		116,512	116,728
Information Technology and Data Processing	12,903		11,717		25,947	23,066
Occupancy, Net	31		11		59	33
Marketing and Advertising Expense	968		744		1,805	1,604
Equipment Expense	1,427		1,309		2,530	2,708
Professional Fees	527		208		1,335	609
Payments of Financing Costs	1,172		1,121		2,516	2,772
Federal Deposit Insurance Corporation Premium Expense	0		0		0	0
Amortization of Intangible Assets	0		0		0	0
Other Noninterest Expense	8,001		5,710		15,491	12,098
Allocated indirect expense	52,884		52,945		105,174	104,368
Commercial and business lending	12,531,178		12,874,874		12,531,178	12,874,874
Assets	13,403,906		13,736,691		13,403,906	13,736,691
Operating Segments | Risk Management and Shared Services [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	(11,849)		(52,411)		(15,690)	(95,677)
Net intersegment interest income (expense)	(29,235)		(36,095)		(71,548)	(72,517)
Segment net interest income	(41,084)		(88,506)		(87,238)	(168,194)
Noninterest Income	3,532		4,610		306	10,678
Provision for Loan, Lease, and Other Losses	(8,735)		925		(20,817)	2,672
Noninterest Expense	28,996		22,902		57,646	43,719
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	(57,813)		(107,722)		(123,761)	(203,906)
Income Tax Expense (Benefit)	(11,316)		(52,589)		(29,520)	(73,716)
Net Income (Loss) Attributable to Parent, Total	(46,497)		(55,133)		(94,241)	(130,191)
Goodwill	0		0		0	0
Interest Income (Expense), before Provision	(37,552)		(83,896)		(86,932)	(157,515)
Interest Income (Expense), after Provision for Loan Loss	(28,817)		(84,821)		(66,115)	(160,187)
Labor and Related Expense	50,204		44,975		92,903	83,371
Information Technology and Data Processing	12,763		14,858		26,267	29,109
Occupancy, Net	12,580		13,117		27,933	26,728
Marketing and Advertising Expense	5,528		5,968		10,143	10,688
Equipment Expense	3,067		3,141		6,491	6,340
Professional Fees	5,927		3,932		11,000	8,068
Payments of Financing Costs	1,273		559		1,712	640
Federal Deposit Insurance Corporation Premium Expense	9,708		7,131		20,144	21,077
Amortization of Intangible Assets	2,203		2,203		4,405	4,405
Other Noninterest Expense	739		(101)		4,442	(2,739)
Allocated indirect expense	(74,996)		(72,881)		(147,794)	(143,969)
Commercial and business lending	458,535		551,574		458,535	551,574
Assets	$ 12,158,236		$ 11,069,628		$ 12,158,236	$ 11,069,628