Loans and Allowance for Credit Losses (Allowance for Credit Losses by Portfolio Class) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 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	6,020	(22,527)
Allowance for loan losses: Ending balance	309,385	317,843
Reserve for unfunded lending commitments: Beginning balance	33,309	29,334
Reserve for unfunded lending commitments: Provision for losses	1,295	1,376
Reserve for unfunded lending commitments: Ending balance	32,014	30,710
Total allowance for credit losses	341,399	348,553
Allowance for loan losses: Individually evaluated		766
Allowance for loan losses: Collectively evaluated	309,385	317,077
Reserve for unfunded lending commitments: Collectively evaluated	32,014	30,710
Loans: Individually evaluated for impairment	13,212	9,587
Loans: Collectively evaluated for impairment	23,391,311	21,313,754
Total loans	23,404,523	21,323,341	$ 23,114,046
Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs	(7,972)	(5,385)
Allowance for loan losses: Recoveries	2,253	5,066
Allowance for loan losses: Net provision for loan losses	7,315	(23,903)
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	76,192	105,367
Reserve for unfunded lending commitments: Beginning balance	1,395	1,694
Reserve for unfunded lending commitments: Provision for losses	493	453
Reserve for unfunded lending commitments: Ending balance	1,888	2,147
Total allowance for credit losses	78,080	107,514
Allowance for loan losses: Individually evaluated		20
Allowance for loan losses: Collectively evaluated	76,192	105,347
Reserve for unfunded lending commitments: Collectively evaluated	1,888	2,147
Loans: Individually evaluated for impairment	1,120	1,309
Loans: Collectively evaluated for impairment	3,757,335	3,561,990
Total loans	3,758,455	3,563,299	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	30,902	21,088
Reserve for unfunded lending commitments: Beginning balance	25,110	21,907
Reserve for unfunded lending commitments: Provision for losses	1,487	(474)
Reserve for unfunded lending commitments: Ending balance	23,623	22,381
Total allowance for credit losses	54,525	43,469
Allowance for loan losses: Individually evaluated		20
Allowance for loan losses: Collectively evaluated	30,902	21,068
Reserve for unfunded lending commitments: Collectively evaluated	23,623	22,381
Loans: Individually evaluated for impairment		122
Loans: Collectively evaluated for impairment	1,726,916	1,286,533
Total loans	1,726,916	1,286,655	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		(4)
Allowance for loan losses: Recoveries		878
Allowance for loan losses: Net provision for loan losses	(4,231)	3,565
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	(61)
Allowance for loan losses: Recoveries	6	68
Allowance for loan losses: Net provision for loan losses	(459)	(1,082)
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	140,312	135,760
Reserve for unfunded lending commitments: Beginning balance	5,286	4,845
Reserve for unfunded lending commitments: Provision for losses	(169)	138
Reserve for unfunded lending commitments: Ending balance	5,117	4,707
Total allowance for credit losses	145,429	140,467
Allowance for loan losses: Individually evaluated		144
Allowance for loan losses: Collectively evaluated	140,312	135,616
Reserve for unfunded lending commitments: Collectively evaluated	5,117	4,707
Loans: Individually evaluated for impairment	10,957	2,693
Loans: Collectively evaluated for impairment	13,053,273	12,450,020
Total loans	13,064,230	12,452,713	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	92,646	87,299
Reserve for unfunded lending commitments: Beginning balance	4,984	4,522
Reserve for unfunded lending commitments: Provision for losses	(191)	246
Reserve for unfunded lending commitments: Ending balance	4,793	4,276
Total allowance for credit losses	97,439	91,575
Allowance for loan losses: Individually evaluated		112
Allowance for loan losses: Collectively evaluated	92,646	87,187
Reserve for unfunded lending commitments: Collectively evaluated	4,793	4,276
Loans: Individually evaluated for impairment	10,273	1,742
Loans: Collectively evaluated for impairment	10,003,209	9,582,738
Total loans	10,013,482	9,584,480	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	47,666	48,461
Reserve for unfunded lending commitments: Beginning balance	302	323
Reserve for unfunded lending commitments: Provision for losses	22	108
Reserve for unfunded lending commitments: Ending balance	324	431
Total allowance for credit losses	47,990	48,892
Allowance for loan losses: Individually evaluated		32
Allowance for loan losses: Collectively evaluated	47,666	48,429
Reserve for unfunded lending commitments: Collectively evaluated	324	431
Loans: Individually evaluated for impairment	684	951
Loans: Collectively evaluated for impairment	3,050,064	2,867,282
Total loans	3,050,748	2,868,233	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	(4,528)	(2,659)
Allowance for loan losses: Recoveries	1,228	2,531
Allowance for loan losses: Net provision for loan losses	(1,133)	(13,433)
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	(4,528)	(2,659)
Allowance for loan losses: Recoveries	1,033	2,142
Allowance for loan losses: Net provision for loan losses	(320)	(8,072)
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: Recoveries	195	389
Allowance for loan losses: Net provision for loan losses	(813)	(5,361)
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	34,541	26,335
Reserve for unfunded lending commitments: Beginning balance	31	22
Reserve for unfunded lending commitments: Provision for losses	(14)	3
Reserve for unfunded lending commitments: Ending balance	17	19
Total allowance for credit losses	34,558	26,354
Allowance for loan losses: Individually evaluated		408
Allowance for loan losses: Collectively evaluated	34,541	25,927
Reserve for unfunded lending commitments: Collectively evaluated	17	19
Loans: Individually evaluated for impairment	1,135	4,534
Loans: Collectively evaluated for impairment	3,328,658	2,458,366
Total loans	3,329,793	2,462,900	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	(20)	(42)
Allowance for loan losses: Recoveries	181	61
Allowance for loan losses: Net provision for loan losses	(1,916)	(4,307)
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	27,438	29,293
Reserve for unfunded lending commitments: Beginning balance	1,487	866
Reserve for unfunded lending commitments: Provision for losses	(118)	590
Reserve for unfunded lending commitments: Ending balance	1,369	1,456
Total allowance for credit losses	28,807	30,749
Allowance for loan losses: Individually evaluated		174
Allowance for loan losses: Collectively evaluated	27,438	29,119
Reserve for unfunded lending commitments: Collectively evaluated	1,369	1,456
Loans: Individually evaluated for impairment		929
Loans: Collectively evaluated for impairment	1,525,129	1,556,845
Total loans	1,525,129	1,557,774	$ 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	(3,363)	(2,680)
Allowance for loan losses: Recoveries	838	1,528
Allowance for loan losses: Net provision for loan losses	$ 1,842	$ 1,516