Segment Reporting (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	$ 305,222			$ 262,509			$ 891,163	$ 776,960
Noninterest Income	81,265			67,221			207,019	197,365
Provision for Loan, Lease, and Other Losses	16,000			20,991			46,999	68,000
Noninterest Expense	216,202			200,597			636,173	594,115
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	154,286			108,142			415,010	312,211
Income Tax Expense (Benefit)	29,554			20,124			77,362	27,451
Net Income (Loss) Attributable to Parent, Total	124,732	$ 111,230	$ 101,687	88,018	$ 115,573	$ 81,169	337,648	284,760
Goodwill	1,104,992						1,104,992		$ 1,104,992
Interest Income (Expense), after Provision for Loan Loss	289,223			241,518			844,164	708,960
Labor and Related Expense	135,703			121,036			386,593	362,012
Information Technology and Data Processing	28,590			27,217			82,237	80,579
Occupancy, Net	12,757			13,536			40,782	40,297
Marketing and Advertising Expense	8,362			6,683			22,496	20,735
Equipment Expense	4,368			4,653			13,389	13,702
Professional Fees	5,232			5,639			17,989	14,740
Federal Deposit Insurance Corporation Premium Expense	9,980			8,223			30,124	29,300
Amortization of Intangible Assets	2,203			2,203			6,608	6,608
Other Noninterest Expense	7,369			8,659			29,017	19,622
Commercial and business lending	30,951,964						30,951,964		29,768,586
Assets	44,455,863						44,455,863		$ 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			200	200
Community, Consumer and Business [Member]
Segment Income Statement Data Abstract
A portion of total depreciation Occupancy expense	2,700			2,400			8,000	9,700
Risk Management and Shared Services [Member]
Segment Income Statement Data Abstract
A portion of total depreciation Equipment expense	9,300			9,600			29,800	39,100
Operating Segments
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	305,222			262,509			891,163	776,960
Net intersegment interest income (expense)	0			0			0	0
Segment net interest income	305,222			262,509			891,163	776,960
Noninterest Income	81,265			67,221			207,019	197,365
Provision for Loan, Lease, and Other Losses	16,000			20,991			46,999	68,000
Noninterest Expense	216,202			200,597			636,173	594,115
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	154,286			108,142			415,010	312,211
Income Tax Expense (Benefit)	29,554			20,124			77,362	27,451
Net Income (Loss) Attributable to Parent, Total	124,732			88,018			337,648	284,760
Goodwill	1,104,992			1,104,992			1,104,992	1,104,992
Interest Income (Expense), before Provision	386,487			329,730			1,098,182	974,325
Interest Income (Expense), after Provision for Loan Loss	370,487			308,739			1,051,183	906,325
Labor and Related Expense	135,703			121,036			386,593	362,012
Information Technology and Data Processing	28,590			27,217			82,237	80,579
Occupancy, Net	12,757			13,536			40,782	40,297
Marketing and Advertising Expense	8,362			6,683			22,496	20,735
Equipment Expense	4,368			4,653			13,389	13,702
Professional Fees	5,232			5,639			17,989	14,740
Payments of Financing Costs	1,638			2,748			6,937	6,519
Federal Deposit Insurance Corporation Premium Expense	9,980			8,223			30,124	29,300
Amortization of Intangible Assets	2,203			2,203			6,608	6,608
Other Noninterest Expense	7,369			8,659			29,017	19,622
Allocated indirect expense	0			0			0	0
Commercial and business lending	30,951,964			29,990,897			30,951,964	29,990,897
Assets	44,455,863			42,210,815			44,455,863	42,210,815
Operating Segments | Corporate and Commercial Specialty [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	246,829			249,343			717,093	734,869
Net intersegment interest income (expense)	(104,695)			(110,149)			(302,467)	(328,433)
Segment net interest income	142,134			139,194			414,626	406,436
Noninterest Income	17,882			12,214			42,770	35,755
Provision for Loan, Lease, and Other Losses	20,424			16,565			59,806	47,602
Noninterest Expense	46,697			42,044			137,653	127,859
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	92,895			92,799			259,937	266,730
Income Tax Expense (Benefit)	17,835			17,255			49,500	49,147
Net Income (Loss) Attributable to Parent, Total	75,060			75,544			210,437	217,585
Goodwill	525,836			525,836			525,836	525,836
Interest Income (Expense), before Provision	160,016			151,408			457,396	442,191
Interest Income (Expense), after Provision for Loan Loss	139,592			134,843			397,590	394,589
Labor and Related Expense	21,287			18,595			62,762	59,472
Information Technology and Data Processing	903			726			2,336	1,914
Occupancy, Net	23			0			56	0
Marketing and Advertising Expense	787			614			2,973	2,374
Equipment Expense	0			0			1	1
Professional Fees	337			197			759	620
Payments of Financing Costs	111			560			1,182	919
Federal Deposit Insurance Corporation Premium Expense	0			0			0	0
Amortization of Intangible Assets	0			0			0	0
Other Noninterest Expense	882			812			2,597	2,416
Allocated indirect expense	22,367			20,540			64,987	60,142
Commercial and business lending	18,033,065			16,482,369			18,033,065	16,482,369
Assets	18,828,850			17,317,618			18,828,850	17,317,618
Operating Segments | Community, Consumer and Business [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	68,027			62,167			199,393	186,768
Net intersegment interest income (expense)	136,142			147,113			405,462	437,914
Segment net interest income	204,169			209,280			604,855	624,682
Noninterest Income	53,670			50,811			154,231	146,736
Provision for Loan, Lease, and Other Losses	6,437			5,639			18,871	18,939
Noninterest Expense	140,132			139,027			411,502	403,013
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	111,270			115,424			328,713	349,466
Income Tax Expense (Benefit)	23,367			24,239			69,030	73,389
Net Income (Loss) Attributable to Parent, Total	87,903			91,185			259,683	276,077
Goodwill	579,156			579,156			579,156	579,156
Interest Income (Expense), before Provision	257,839			260,090			759,086	771,418
Interest Income (Expense), after Provision for Loan Loss	251,402			254,451			740,215	752,479
Labor and Related Expense	62,335			60,098			178,847	176,826
Information Technology and Data Processing	13,179			12,285			39,126	35,351
Occupancy, Net	24			10			83	43
Marketing and Advertising Expense	778			725			2,583	2,329
Equipment Expense	1,274			1,570			3,804	4,278
Professional Fees	563			781			1,898	1,391
Payments of Financing Costs	979			1,334			3,495	4,106
Federal Deposit Insurance Corporation Premium Expense	0			0			0	0
Amortization of Intangible Assets	0			0			0	0
Other Noninterest Expense	7,769			7,854			23,260	19,951
Allocated indirect expense	53,231			54,370			158,406	158,738
Commercial and business lending	12,481,836			12,985,873			12,481,836	12,985,873
Assets	13,333,059			13,832,358			13,333,059	13,832,358
Operating Segments | Risk Management and Shared Services [Member]
Segment Income Statement Data Abstract
Interest Income (Expense), Operating	(9,634)			(49,001)			(25,323)	(144,677)
Net intersegment interest income (expense)	(31,447)			(36,964)			(102,995)	(109,481)
Segment net interest income	(41,081)			(85,964)			(128,318)	(254,158)
Noninterest Income	9,713			4,196			10,018	14,874
Provision for Loan, Lease, and Other Losses	(10,861)			(1,213)			(31,678)	1,459
Noninterest Expense	29,373			19,526			87,018	63,245
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest, Total	(49,880)			(100,081)			(173,640)	(303,988)
Income Tax Expense (Benefit)	(11,648)			(21,370)			(41,168)	(95,085)
Net Income (Loss) Attributable to Parent, Total	(38,231)			(78,711)			(132,472)	(208,902)
Goodwill	0			0			0	0
Interest Income (Expense), before Provision	(31,368)			(81,768)			(118,300)	(239,284)
Interest Income (Expense), after Provision for Loan Loss	(20,507)			(80,555)			(86,622)	(240,743)
Labor and Related Expense	52,081			42,343			144,984	125,714
Information Technology and Data Processing	14,508			14,206			40,775	43,314
Occupancy, Net	12,710			13,526			40,643	40,254
Marketing and Advertising Expense	6,797			5,344			16,940	16,032
Equipment Expense	3,094			3,083			9,584	9,423
Professional Fees	4,332			4,661			15,332	12,729
Payments of Financing Costs	548			854			2,260	1,494
Federal Deposit Insurance Corporation Premium Expense	9,980			8,223			30,124	29,300
Amortization of Intangible Assets	2,203			2,203			6,608	6,608
Other Noninterest Expense	(1,282)			(7)			3,160	(2,745)
Allocated indirect expense	(75,598)			(74,910)			(223,393)	(218,880)
Commercial and business lending	437,063			522,655			437,063	522,655
Assets	$ 12,293,954			$ 11,060,839			$ 12,293,954	$ 11,060,839