Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2026	Mar. 31, 2026	Jun. 30, 2025	Mar. 31, 2025	Jun. 30, 2026	Jun. 30, 2025	Apr. 01, 2026	Dec. 31, 2025
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	$ 370,039		$ 300,000		$ 677,228	$ 585,940
Noninterest Income	80,398		66,977		156,256	125,754
Provision for Loan, Lease, and Other Losses	19,388		17,996		30,389	30,999
Noninterest Expense	271,882		209,352		491,045	419,971
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	159,167		139,629		312,050	260,724
Income Tax Expense (Benefit)	35,603		28,399		68,850	47,808
Net Income (Loss) Attributable to Parent, Total	123,564	$ 119,635	111,230	$ 101,687	243,200	212,916
Goodwill	1,147,081				1,147,081		$ 42,100	$ 1,104,992
Interest Income (Expense), after Provision for Loan Loss	350,651		282,004		646,839	554,941
Labor and Related Expense	161,168		126,994		296,341	250,890
Information Technology and Data Processing	32,867		26,508		62,603	53,646
Occupancy, Net	14,091		12,644		27,817	28,025
Marketing and Advertising Expense	8,548		7,748		16,374	14,134
Equipment Expense	5,423		4,494		11,033	9,021
Professional Fees	17,454		6,674		24,176	12,757
Federal Deposit Insurance Corporation Premium Expense	10,595		9,708		19,432	20,144
Amortization of Intangible Assets	6,894		2,203		9,096	4,405
Other Noninterest Expense	13,290		9,674		20,914	21,648
Commercial and business lending	36,467,040				36,467,040			31,163,614
Assets	51,812,506				51,812,506			$ 45,202,596
Gain (Loss) on Sale of Mortgage Loans	0		0		0	(6,976)
Corporate and Commercial Specialty [Member]
Segment Income Statement Data Abstract
A portion of total depreciation Technology expense	200		100		300	100
Community, Consumer and Business [Member]
Segment Income Statement Data Abstract
A portion of total depreciation Occupancy expense	6,300		5,900		12,500	11,800
Risk Management and Shared Services [Member]
Segment Income Statement Data Abstract
A portion of total depreciation Equipment expense	6,000		6,000		11,900	14,000
Operating Segments
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	370,039		300,000		677,228	585,940
Net intersegment interest income (expense)	0		0		0	0
Segment net interest income	370,039		300,000		677,228	585,940
Noninterest Income	80,398		66,977		156,256	125,754
Provision for Loan, Lease, and Other Losses	19,388		17,996		30,389	30,999
Noninterest Expense	271,882		209,352		491,045	419,971
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	159,167		139,629		312,050	260,724
Income Tax Expense (Benefit)	35,603		28,399		68,850	47,808
Net Income (Loss) Attributable to Parent, Total	123,564		111,230		243,200	212,916
Goodwill	1,147,081		1,104,992		1,147,081	1,104,992
Interest Income (Expense), before Provision	450,437		366,977		833,484	711,694
Interest Income (Expense), after Provision for Loan Loss	431,049		348,981		803,095	680,695
Labor and Related Expense	161,168		126,994		296,341	250,890
Information Technology and Data Processing	32,867		26,508		62,603	53,646
Occupancy, Net	14,091		12,644		27,817	28,025
Marketing and Advertising Expense	8,548		7,748		16,374	14,134
Equipment Expense	5,423		4,494		11,033	9,021
Professional Fees	17,454		6,674		24,176	12,757
Payments of Financing Costs	1,552		2,705		3,259	5,299
Federal Deposit Insurance Corporation Premium Expense	10,595		9,708		19,432	20,144
Amortization of Intangible Assets	6,894		2,203		9,096	4,405
Other Noninterest Expense	13,290		9,674		20,914	21,648
Allocated indirect expense	0		0		0	0
Commercial and business lending	36,467,040		30,607,605		36,467,040	30,607,605
Assets	51,812,506		43,993,729		51,812,506	43,993,729
Operating Segments | Corporate and Commercial Specialty [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	267,324		242,978		498,429	470,263
Net intersegment interest income (expense)	(105,641)		(107,337)		(208,353)	(203,557)
Segment net interest income	161,683		135,641		290,076	266,706
Noninterest Income	15,648		11,984		29,540	24,887
Provision for Loan, Lease, and Other Losses	21,287		20,369		41,947	39,382
Noninterest Expense	58,400		56,021		108,131	112,155
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	97,644		71,236		169,538	140,056
Income Tax Expense (Benefit)	17,567		13,211		30,825	25,997
Net Income (Loss) Attributable to Parent, Total	80,077		58,025		138,713	114,059
Goodwill	556,343		525,836		556,343	525,836
Interest Income (Expense), before Provision	177,331		147,625		319,616	291,593
Interest Income (Expense), after Provision for Loan Loss	156,044		127,256		277,669	252,211
Labor and Related Expense	24,595		20,149		48,145	41,475
Information Technology and Data Processing	1,293		842		2,116	1,432
Occupancy, Net	255		190		473	336
Marketing and Advertising Expense	1,128		1,252		2,097	2,186
Equipment Expense	6		6		12	12
Professional Fees	272		221		529	422
Payments of Financing Costs	233		261		721	1,071
Federal Deposit Insurance Corporation Premium Expense	0		0		0	0
Amortization of Intangible Assets	0		0		0	0
Other Noninterest Expense	1,087		934		1,808	1,714
Allocated indirect expense	29,531		32,166		52,230	63,505
Commercial and business lending	21,736,674		17,617,892		21,736,674	17,617,892
Assets	22,552,085		17,907,721		22,552,085	17,907,721
Operating Segments | Community, Consumer and Business [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	86,481		68,871		154,917	131,367
Net intersegment interest income (expense)	136,046		143,478		266,076	288,856
Segment net interest income	222,527		212,349		420,993	420,223
Noninterest Income	56,437		51,481		112,380	100,560
Provision for Loan, Lease, and Other Losses	6,456		6,363		13,391	12,434
Noninterest Expense	174,545		153,331		330,630	307,816
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	97,963		104,137		189,352	200,533
Income Tax Expense (Benefit)	20,676		21,869		39,868	42,112
Net Income (Loss) Attributable to Parent, Total	77,287		82,268		149,484	158,421
Goodwill	590,738		579,156		590,738	579,156
Interest Income (Expense), before Provision	278,964		263,830		533,373	520,783
Interest Income (Expense), after Provision for Loan Loss	272,508		257,467		519,982	508,349
Labor and Related Expense	65,456		56,641		130,410	116,513
Information Technology and Data Processing	13,853		12,903		27,978	25,947
Occupancy, Net	8,405		7,386		16,756	15,820
Marketing and Advertising Expense	839		968		1,527	1,805
Equipment Expense	2,319		2,301		4,395	4,331
Professional Fees	1,478		529		2,160	1,343
Payments of Financing Costs	1,296		1,171		2,236	2,516
Federal Deposit Insurance Corporation Premium Expense	0		0		0	0
Amortization of Intangible Assets	0		0		0	0
Other Noninterest Expense	10,376		8,024		18,058	15,427
Allocated indirect expense	70,523		63,408		127,110	124,114
Commercial and business lending	14,231,238		12,531,178		14,231,238	12,531,178
Assets	15,452,018		13,043,969		15,452,018	13,043,969
Operating Segments | Risk Management and Shared Services [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	16,234		(11,849)		23,882	(15,690)
Net intersegment interest income (expense)	(30,405)		(36,141)		(57,723)	(85,299)
Segment net interest income	(14,171)		(47,990)		(33,841)	(100,989)
Noninterest Income	8,313		3,512		14,336	307
Provision for Loan, Lease, and Other Losses	(8,355)		(8,736)		(24,949)	(20,817)
Noninterest Expense	38,937		0		52,284	0
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	(36,440)		(35,744)		(46,840)	(79,865)
Income Tax Expense (Benefit)	(2,640)		(6,681)		(1,843)	(20,301)
Net Income (Loss) Attributable to Parent, Total	(33,800)		(29,063)		(44,997)	(59,564)
Goodwill	0		0		0	0
Interest Income (Expense), before Provision	(5,858)		(44,478)		(19,505)	(100,682)
Interest Income (Expense), after Provision for Loan Loss	2,497		(35,742)		5,444	(79,865)
Labor and Related Expense	71,117		50,204		117,786	92,902
Information Technology and Data Processing	17,721		12,763		32,509	26,267
Occupancy, Net	5,431		5,068		10,588	11,869
Marketing and Advertising Expense	6,581		5,528		12,750	10,143
Equipment Expense	3,098		2,187		6,626	4,678
Professional Fees	15,704		5,924		21,487	10,992
Payments of Financing Costs	23		1,273		302	1,712
Federal Deposit Insurance Corporation Premium Expense	10,595		9,708		19,432	20,144
Amortization of Intangible Assets	6,894		2,203		9,096	4,405
Other Noninterest Expense	1,827		716		1,048	4,507
Allocated indirect expense	(100,054)		(95,574)		(179,340)	(187,619)
Commercial and business lending	499,128		458,535		499,128	458,535
Assets	$ 13,808,403		$ 13,042,039		$ 13,808,403	$ 13,042,039