Loans and Allowance for Credit Losses (Allowance for Credit Losses by Portfolio Class) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 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	12,968	6,020
Allowance for loan losses: Ending balance	313,726	309,385
Reserve for unfunded lending commitments: Beginning balance	28,894	33,309
Reserve for unfunded lending commitments: Provision for losses	(1,831)	(1,295)
Reserve for unfunded lending commitments: Ending balance	27,063	32,014
Total allowance for credit losses	340,789	341,399
Allowance for loan losses: Individually evaluated		0
Allowance for loan losses: Collectively evaluated	313,726	309,385
Reserve for unfunded lending commitments: Individually evaluated		0
Reserve for unfunded lending commitments: Collectively evaluated	27,063	32,014
Loans: Individually evaluated for impairment	37,176	13,212
Loans: Collectively evaluated for impairment	23,933,762	23,391,311
Total loans	23,970,938	23,404,523	$ 23,921,917
Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs	(23,366)	(7,972)
Allowance for loan losses: Recoveries	14,386	2,253
Allowance for loan losses: Net provision for loan losses	14,799	7,315
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	77,877	76,192
Reserve for unfunded lending commitments: Beginning balance	1,344	1,395
Reserve for unfunded lending commitments: Provision for losses	(352)	493
Reserve for unfunded lending commitments: Ending balance	992	1,888
Total allowance for credit losses	78,869	78,080
Allowance for loan losses: Individually evaluated		0
Allowance for loan losses: Collectively evaluated	77,877	76,192
Reserve for unfunded lending commitments: Individually evaluated		0
Reserve for unfunded lending commitments: Collectively evaluated	992	1,888
Loans: Individually evaluated for impairment	23,436	1,120
Loans: Collectively evaluated for impairment	4,019,361	3,757,335
Total loans	4,042,797	3,758,455	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	25,838	30,902
Reserve for unfunded lending commitments: Beginning balance	20,019	25,110
Reserve for unfunded lending commitments: Provision for losses	(1,615)	(1,487)
Reserve for unfunded lending commitments: Ending balance	18,404	23,623
Total allowance for credit losses	44,242	54,525
Allowance for loan losses: Individually evaluated		0
Allowance for loan losses: Collectively evaluated	25,838	30,902
Reserve for unfunded lending commitments: Individually evaluated		0
Reserve for unfunded lending commitments: Collectively evaluated	18,404	23,623
Loans: Individually evaluated for impairment	928	0
Loans: Collectively evaluated for impairment	1,540,845	1,726,916
Total loans	1,541,773	1,726,916	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)	0
Allowance for loan losses: Recoveries	3	0
Allowance for loan losses: Net provision for loan losses	12,154	4,231
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	(75)	(61)
Allowance for loan losses: Recoveries	61	6
Allowance for loan losses: Net provision for loan losses	(1,187)	459
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	143,636	140,312
Reserve for unfunded lending commitments: Beginning balance	5,834	5,286
Reserve for unfunded lending commitments: Provision for losses	152	(169)
Reserve for unfunded lending commitments: Ending balance	5,986	5,117
Total allowance for credit losses	149,622	145,429
Allowance for loan losses: Individually evaluated		0
Allowance for loan losses: Collectively evaluated	143,636	140,312
Reserve for unfunded lending commitments: Individually evaluated		0
Reserve for unfunded lending commitments: Collectively evaluated	5,986	5,117
Loans: Individually evaluated for impairment	11,994	10,957
Loans: Collectively evaluated for impairment	12,994,531	13,053,273
Total loans	13,006,525	13,064,230	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	104,358	92,646
Reserve for unfunded lending commitments: Beginning balance	5,507	4,984
Reserve for unfunded lending commitments: Provision for losses	192	(191)
Reserve for unfunded lending commitments: Ending balance	5,699	4,793
Total allowance for credit losses	110,057	97,439
Allowance for loan losses: Individually evaluated		0
Allowance for loan losses: Collectively evaluated	104,358	92,646
Reserve for unfunded lending commitments: Individually evaluated		0
Reserve for unfunded lending commitments: Collectively evaluated	5,699	4,793
Loans: Individually evaluated for impairment	11,255	10,273
Loans: Collectively evaluated for impairment	9,915,078	10,003,209
Total loans	9,926,333	10,013,482	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	39,278	47,666
Reserve for unfunded lending commitments: Beginning balance	327	302
Reserve for unfunded lending commitments: Provision for losses	(40)	22
Reserve for unfunded lending commitments: Ending balance	287	324
Total allowance for credit losses	39,565	47,990
Allowance for loan losses: Individually evaluated		0
Allowance for loan losses: Collectively evaluated	39,278	47,666
Reserve for unfunded lending commitments: Individually evaluated		0
Reserve for unfunded lending commitments: Collectively evaluated	287	324
Loans: Individually evaluated for impairment	739	684
Loans: Collectively evaluated for impairment	3,079,453	3,050,064
Total loans	3,080,192	3,050,748	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	(9,630)	(4,528)
Allowance for loan losses: Recoveries	13,206	1,228
Allowance for loan losses: Net provision for loan losses	(1,874)	(1,133)
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	(9,630)	(4,528)
Allowance for loan losses: Recoveries	13,104	1,033
Allowance for loan losses: Net provision for loan losses	(853)	(320)
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	102	195
Allowance for loan losses: Net provision for loan losses	(1,021)	(813)
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	41,158	34,541
Reserve for unfunded lending commitments: Beginning balance	30	31
Reserve for unfunded lending commitments: Provision for losses	(8)	(14)
Reserve for unfunded lending commitments: Ending balance	22	17
Total allowance for credit losses	41,180	34,558
Allowance for loan losses: Individually evaluated		0
Allowance for loan losses: Collectively evaluated	41,158	34,541
Reserve for unfunded lending commitments: Individually evaluated		0
Reserve for unfunded lending commitments: Collectively evaluated	22	17
Loans: Individually evaluated for impairment		1,135
Loans: Collectively evaluated for impairment	3,983,321	3,328,658
Total loans	3,983,321	3,329,793	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	(56)	(20)
Allowance for loan losses: Recoveries	202	181
Allowance for loan losses: Net provision for loan losses	2,029	1,916
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	25,217	27,438
Reserve for unfunded lending commitments: Beginning balance	1,667	1,487
Reserve for unfunded lending commitments: Provision for losses	(8)	(118)
Reserve for unfunded lending commitments: Ending balance	1,659	1,369
Total allowance for credit losses	26,876	28,807
Allowance for loan losses: Individually evaluated		0
Allowance for loan losses: Collectively evaluated	25,217	27,438
Reserve for unfunded lending commitments: Individually evaluated		0
Reserve for unfunded lending commitments: Collectively evaluated	1,659	1,369
Loans: Individually evaluated for impairment	818	0
Loans: Collectively evaluated for impairment	1,395,704	1,525,129
Total loans	1,396,522	1,525,129	$ 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	(4,786)	(3,363)
Allowance for loan losses: Recoveries	914	838
Allowance for loan losses: Net provision for loan losses	$ 3,677	$ 1,842