Loans and Allowance for Credit Losses (Allowance for Credit Losses by Portfolio Class) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			$ 307,907	$ 307,789
Allowance for loan losses: Net provision for loan losses	$ 18,564	$ 28,498	40,255	42,151
Allowance for loan losses: Ending balance	317,271	306,291	317,271	306,291
Reserve for unfunded lending commitments: Beginning balance			28,894	33,309
Reserve for unfunded lending commitments: Provision for losses			(3,401)	(3,696)
Reserve for unfunded lending commitments: Ending balance	25,493	29,613	25,493	29,613
Total allowance for credit losses	342,764	335,904	342,764	335,904
Allowance for loan losses: Individually evaluated	5,281	0	5,281	0
Allowance for loan losses: Collectively evaluated	311,990	304,625	311,990	304,625
Reserve for unfunded lending commitments: Individually evaluated	713	1,666	713	1,666
Reserve for unfunded lending commitments: Collectively evaluated	24,780	29,613	24,780	29,613
Loans: Individually evaluated for impairment	26,016	17,658	26,016	17,658
Loans: Collectively evaluated for impairment	23,429,571	23,966,021	23,429,571	23,966,021
Total loans	23,455,587	23,983,679	23,455,587	23,983,679	$ 23,921,917
Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(56,430)	(55,822)
Allowance for loan losses: Recoveries			22,138	8,477
Allowance for loan losses: Net provision for loan losses			43,656	45,847
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			74,539	71,961
Allowance for loan losses: Ending balance	78,467	74,341	78,467	74,341
Reserve for unfunded lending commitments: Beginning balance			1,344	1,395
Reserve for unfunded lending commitments: Provision for losses			(353)	39
Reserve for unfunded lending commitments: Ending balance	991	1,434	991	1,434
Total allowance for credit losses	79,458	75,775	79,458	75,775
Allowance for loan losses: Individually evaluated		0		0
Allowance for loan losses: Collectively evaluated	78,467	74,341	78,467	74,341
Reserve for unfunded lending commitments: Individually evaluated		0		0
Reserve for unfunded lending commitments: Collectively evaluated	991	1,434	991	1,434
Loans: Individually evaluated for impairment	1,679	0	1,679	0
Loans: Collectively evaluated for impairment	3,986,982	4,027,553	3,986,982	4,027,553
Total loans	3,988,661	4,027,553	3,988,661	4,027,553	3,986,943
Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			27,039	30,498
Allowance for loan losses: Ending balance	24,793	28,223	24,793	28,223
Reserve for unfunded lending commitments: Beginning balance			20,019	25,110
Reserve for unfunded lending commitments: Provision for losses			(4,250)	(3,874)
Reserve for unfunded lending commitments: Ending balance	15,769	21,236	15,769	21,236
Total allowance for credit losses	40,562	49,459	40,562	49,459
Allowance for loan losses: Individually evaluated		0		0
Allowance for loan losses: Collectively evaluated	24,793	28,223	24,793	28,223
Reserve for unfunded lending commitments: Individually evaluated		0		0
Reserve for unfunded lending commitments: Collectively evaluated	15,769	21,236	15,769	21,236
Loans: Individually evaluated for impairment	5,694	0	5,694	0
Loans: Collectively evaluated for impairment	1,417,921	1,614,846	1,417,921	1,614,846
Total loans	1,423,615	1,614,846	1,423,615	1,614,846	1,551,091
Total Commercial [Member] | Non-Purchased Credit Impaired Loans [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(8,819)	(73)
Allowance for loan losses: Recoveries			7	12
Allowance for loan losses: Net provision for loan losses			12,740	2,441
Total Commercial [Member] | Non-Purchased Credit Impaired Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(264)	(72)
Allowance for loan losses: Recoveries			62	10
Allowance for loan losses: Net provision for loan losses			(2,044)	(2,213)
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			141,934	144,745
Allowance for loan losses: Ending balance	146,283	141,244	146,283	141,244
Reserve for unfunded lending commitments: Beginning balance			5,834	5,286
Reserve for unfunded lending commitments: Provision for losses			709	280
Reserve for unfunded lending commitments: Ending balance	6,543	5,566	6,543	5,566
Total allowance for credit losses	152,826	146,810	152,826	146,810
Allowance for loan losses: Individually evaluated	4,334	0	4,334	0
Allowance for loan losses: Collectively evaluated	141,949	139,578	141,949	139,578
Reserve for unfunded lending commitments: Individually evaluated	713	1,666	713	1,666
Reserve for unfunded lending commitments: Collectively evaluated	5,830	5,566	5,830	5,566
Loans: Individually evaluated for impairment	13,654	17,658	13,654	17,658
Loans: Collectively evaluated for impairment	12,670,828	13,139,254	12,670,828	13,139,254
Total loans	12,684,482	13,156,912	12,684,482	13,156,912	13,051,047
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			101,737	96,461
Allowance for loan losses: Ending balance	108,743	99,665	108,743	99,665
Reserve for unfunded lending commitments: Beginning balance			5,507	4,984
Reserve for unfunded lending commitments: Provision for losses			752	270
Reserve for unfunded lending commitments: Ending balance	6,259	5,254	6,259	5,254
Total allowance for credit losses	115,002	104,919	115,002	104,919
Allowance for loan losses: Individually evaluated	4,283	0	4,283	0
Allowance for loan losses: Collectively evaluated	104,460	97,999	104,460	97,999
Reserve for unfunded lending commitments: Individually evaluated	713	1,666	713	1,666
Reserve for unfunded lending commitments: Collectively evaluated	5,546	5,254	5,546	5,254
Loans: Individually evaluated for impairment	12,435	17,658	12,435	17,658
Loans: Collectively evaluated for impairment	9,575,874	10,057,927	9,575,874	10,057,927
Total loans	9,588,309	10,075,585	9,588,309	10,075,585	9,957,284
Total Commercial [Member] | Total Commercial And Industrial [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			40,197	48,284
Allowance for loan losses: Ending balance	37,540	41,579	37,540	41,579
Reserve for unfunded lending commitments: Beginning balance			327	302
Reserve for unfunded lending commitments: Provision for losses			(43)	10
Reserve for unfunded lending commitments: Ending balance	284	312	284	312
Total allowance for credit losses	37,824	41,891	37,824	41,891
Allowance for loan losses: Individually evaluated	51	0	51	0
Allowance for loan losses: Collectively evaluated	37,489	41,579	37,489	41,579
Reserve for unfunded lending commitments: Collectively evaluated	284	312	284	312
Loans: Individually evaluated for impairment	1,219	0	1,219	0
Loans: Collectively evaluated for impairment	3,094,954	3,081,327	3,094,954	3,081,327
Total loans	3,096,173	3,081,327	3,096,173	3,081,327	3,093,763
Total Commercial [Member] | Total Commercial And Industrial [Member] | Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(33,869)	(44,837)
Allowance for loan losses: Recoveries			19,053	4,866
Allowance for loan losses: Net provision for loan losses			19,165	36,470
Total Commercial [Member] | Total Commercial And Industrial [Member] | Non-Purchased Credit Impaired Loans [Member] | Commercial Non-Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(33,869)	(44,837)
Allowance for loan losses: Recoveries			18,067	4,419
Allowance for loan losses: Net provision for loan losses			22,808	43,622
Total Commercial [Member] | Total Commercial And Industrial [Member] | Non-Purchased Credit Impaired Loans [Member] | Commercial Real Estate - Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs				0
Allowance for loan losses: Recoveries			986	447
Allowance for loan losses: Net provision for loan losses			(3,643)	(7,152)
Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			38,983	32,464
Allowance for loan losses: Ending balance	42,857	36,862	42,857	36,862
Reserve for unfunded lending commitments: Beginning balance			30	31
Reserve for unfunded lending commitments: Provision for losses			(27)	4
Reserve for unfunded lending commitments: Ending balance	3	35	3	35
Total allowance for credit losses	42,860	36,897	42,860	36,897
Allowance for loan losses: Individually evaluated	750	0	750	0
Allowance for loan losses: Collectively evaluated	42,107	36,862	42,107	36,862
Reserve for unfunded lending commitments: Individually evaluated		0		0
Reserve for unfunded lending commitments: Collectively evaluated	3	35	3	35
Loans: Individually evaluated for impairment	1,893	0	1,893	0
Loans: Collectively evaluated for impairment	3,986,416	3,721,106	3,986,416	3,721,106
Total loans	3,988,309	3,721,106	3,988,309	3,721,106	3,886,072
Residential Mortgages [Member] | Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(229)	(53)
Allowance for loan losses: Recoveries			430	888
Allowance for loan losses: Net provision for loan losses			3,673	3,563
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			25,412	28,121
Allowance for loan losses: Ending balance	24,871	25,621	24,871	25,621
Reserve for unfunded lending commitments: Beginning balance			1,667	1,487
Reserve for unfunded lending commitments: Provision for losses			520	(145)
Reserve for unfunded lending commitments: Ending balance	2,187	1,342	2,187	1,342
Total allowance for credit losses	27,058	26,963	27,058	26,963
Allowance for loan losses: Individually evaluated	197	0	197	0
Allowance for loan losses: Collectively evaluated	24,674	25,621	24,674	25,621
Reserve for unfunded lending commitments: Individually evaluated		0		0
Reserve for unfunded lending commitments: Collectively evaluated	2,187	1,342	2,187	1,342
Loans: Individually evaluated for impairment	3,096	0	3,096	0
Loans: Collectively evaluated for impairment	1,367,424	1,463,262	1,367,424	1,463,262
Total loans	$ 1,370,520	$ 1,463,262	1,370,520	1,463,262	$ 1,446,764
Consumer [Member] | Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(13,249)	(10,787)
Allowance for loan losses: Recoveries			2,586	2,701
Allowance for loan losses: Net provision for loan losses			$ 10,122	$ 5,586