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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			$ 307,789	$ 342,065
Allowance for loan losses: Net provision for loan losses	$ 28,498	$ 1,402	42,151	(30,886)
Allowance for loan losses: Ending balance	306,291	306,116	306,291	306,116
Reserve for unfunded lending commitments: Beginning balance			33,309	29,334
Reserve for unfunded lending commitments: Provision for losses			(3,696)	4,134
Reserve for unfunded lending commitments: Ending balance	29,613	33,468	29,613	33,468
Total allowance for credit losses	335,904	339,584	335,904	339,584
Allowance for loan losses: Individually evaluated	1,666	516	1,666	516
Allowance for loan losses: Collectively evaluated	304,625	305,600	304,625	305,600
Reserve for unfunded lending commitments: Individually evaluated		3		3
Reserve for unfunded lending commitments: Collectively evaluated	29,613	33,465	29,613	33,465
Loans: Individually evaluated for impairment	17,658	7,806	17,658	7,806
Loans: Collectively evaluated for impairment	23,966,021	22,577,779	23,966,021	22,577,779
Total loans	23,983,679	22,585,585	23,983,679	22,585,585	$ 23,114,046
Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(55,822)	(17,947)
Allowance for loan losses: Recoveries			8,477	17,018
Allowance for loan losses: Net provision for loan losses			45,847	(35,020)
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			71,961	108,058
Allowance for loan losses: Ending balance	74,341	77,412	74,341	77,412
Reserve for unfunded lending commitments: Beginning balance			1,395	1,694
Reserve for unfunded lending commitments: Provision for losses			39	(205)
Reserve for unfunded lending commitments: Ending balance	1,434	1,489	1,434	1,489
Total allowance for credit losses	75,775	78,901	75,775	78,901
Allowance for loan losses: Individually evaluated		17		17
Allowance for loan losses: Collectively evaluated	74,341	77,395	74,341	77,395
Reserve for unfunded lending commitments: Collectively evaluated	1,434	1,489	1,434	1,489
Loans: Individually evaluated for impairment		1,270		1,270
Loans: Collectively evaluated for impairment	4,027,553	3,685,270	4,027,553	3,685,270
Total loans	4,027,553	3,686,540	4,027,553	3,686,540	3,560,991
Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			30,498	22,102
Allowance for loan losses: Ending balance	28,223	26,747	28,223	26,747
Reserve for unfunded lending commitments: Beginning balance			25,110	21,907
Reserve for unfunded lending commitments: Provision for losses			(3,874)	3,602
Reserve for unfunded lending commitments: Ending balance	21,236	25,509	21,236	25,509
Total allowance for credit losses	49,459	52,256	49,459	52,256
Allowance for loan losses: Individually evaluated		19		19
Allowance for loan losses: Collectively evaluated	28,223	26,728	28,223	26,728
Reserve for unfunded lending commitments: Collectively evaluated	21,236	25,509	21,236	25,509
Loans: Individually evaluated for impairment		118		118
Loans: Collectively evaluated for impairment	1,614,846	1,541,139	1,614,846	1,541,139
Total loans	1,614,846	1,541,257	1,614,846	1,541,257	1,703,592
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			(73)	(1,066)
Allowance for loan losses: Recoveries			12	878
Allowance for loan losses: Net provision for loan losses			2,441	(30,458)
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			(72)	(3)
Allowance for loan losses: Recoveries			10	132
Allowance for loan losses: Net provision for loan losses			(2,213)	4,516
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			144,745	149,321
Allowance for loan losses: Ending balance	141,244	142,823	141,244	142,823
Reserve for unfunded lending commitments: Beginning balance			5,286	4,845
Reserve for unfunded lending commitments: Provision for losses			280	248
Reserve for unfunded lending commitments: Ending balance	5,566	5,093	5,566	5,093
Total allowance for credit losses	146,810	147,916	146,810	147,916
Allowance for loan losses: Individually evaluated	1,666	102	1,666	102
Allowance for loan losses: Collectively evaluated	139,578	142,721	139,578	142,721
Reserve for unfunded lending commitments: Individually evaluated		3		3
Reserve for unfunded lending commitments: Collectively evaluated	5,566	5,090	5,566	5,090
Loans: Individually evaluated for impairment	17,658	2,211	17,658	2,211
Loans: Collectively evaluated for impairment	13,139,254	12,936,349	13,139,254	12,936,349
Total loans	13,156,912	12,938,560	13,156,912	12,938,560	13,179,511
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			96,461	95,888
Allowance for loan losses: Ending balance	99,665	94,806	99,665	94,806
Reserve for unfunded lending commitments: Beginning balance			4,984	4,522
Reserve for unfunded lending commitments: Provision for losses			270	238
Reserve for unfunded lending commitments: Ending balance	5,254	4,760	5,254	4,760
Total allowance for credit losses	104,919	99,566	104,919	99,566
Allowance for loan losses: Individually evaluated	1,666	71	1,666	71
Allowance for loan losses: Collectively evaluated	97,999	94,735	97,999	94,735
Reserve for unfunded lending commitments: Individually evaluated		3		3
Reserve for unfunded lending commitments: Collectively evaluated	5,254	4,757	5,254	4,757
Loans: Individually evaluated for impairment	17,658	1,282	17,658	1,282
Loans: Collectively evaluated for impairment	10,057,927	9,904,145	10,057,927	9,904,145
Total loans	10,075,585	9,905,427	10,075,585	9,905,427	10,146,453
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			48,284	53,433
Allowance for loan losses: Ending balance	41,579	48,017	41,579	48,017
Reserve for unfunded lending commitments: Beginning balance			302	323
Reserve for unfunded lending commitments: Provision for losses			10	10
Reserve for unfunded lending commitments: Ending balance	312	333	312	333
Total allowance for credit losses	41,891	48,350	41,891	48,350
Allowance for loan losses: Individually evaluated		31		31
Allowance for loan losses: Collectively evaluated	41,579	47,986	41,579	47,986
Reserve for unfunded lending commitments: Collectively evaluated	312	333	312	333
Loans: Individually evaluated for impairment		929		929
Loans: Collectively evaluated for impairment	3,081,327	3,032,204	3,081,327	3,032,204
Total loans	3,081,327	3,033,133	3,081,327	3,033,133	3,033,058
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			(44,837)	(7,312)
Allowance for loan losses: Recoveries			4,866	10,066
Allowance for loan losses: Net provision for loan losses			36,470	(9,252)
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			(44,837)	(6,366)
Allowance for loan losses: Recoveries			4,419	9,460
Allowance for loan losses: Net provision for loan losses			43,622	(4,176)
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				(946)
Allowance for loan losses: Recoveries			447	606
Allowance for loan losses: Net provision for loan losses			(7,152)	(5,076)
Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			32,464	30,623
Allowance for loan losses: Ending balance	36,862	30,947	36,862	30,947
Reserve for unfunded lending commitments: Beginning balance			31	22
Reserve for unfunded lending commitments: Provision for losses			4	(5)
Reserve for unfunded lending commitments: Ending balance	35	17	35	17
Total allowance for credit losses	36,897	30,964	36,897	30,964
Allowance for loan losses: Individually evaluated		276		276
Allowance for loan losses: Collectively evaluated	36,862	30,671	36,862	30,671
Reserve for unfunded lending commitments: Collectively evaluated	35	17	35	17
Loans: Individually evaluated for impairment		3,680		3,680
Loans: Collectively evaluated for impairment	3,721,106	2,840,043	3,721,106	2,840,043
Total loans	3,721,106	2,843,723	3,721,106	2,843,723	3,092,605
Residential Mortgages [Member] | Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(53)	(102)
Allowance for loan losses: Recoveries			888	1,463
Allowance for loan losses: Net provision for loan losses			3,563	(1,037)
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			28,121	31,961
Allowance for loan losses: Ending balance	25,621	28,187	25,621	28,187
Reserve for unfunded lending commitments: Beginning balance			1,487	866
Reserve for unfunded lending commitments: Provision for losses			(145)	494
Reserve for unfunded lending commitments: Ending balance	1,342	1,360	1,342	1,360
Total allowance for credit losses	26,963	29,547	26,963	29,547
Allowance for loan losses: Individually evaluated		102		102
Allowance for loan losses: Collectively evaluated	25,621	28,085	25,621	28,085
Reserve for unfunded lending commitments: Collectively evaluated	1,342	1,360	1,342	1,360
Loans: Individually evaluated for impairment		527		527
Loans: Collectively evaluated for impairment	1,463,262	1,574,978	1,463,262	1,574,978
Total loans	$ 1,463,262	$ 1,575,505	1,463,262	1,575,505	$ 1,577,347
Consumer [Member] | Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(10,787)	(9,464)
Allowance for loan losses: Recoveries			2,701	4,479
Allowance for loan losses: Net provision for loan losses			$ 5,586	$ 1,211