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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			$ 342,065	$ 450,177
Allowance for loan losses: Net provision for loan losses	$ 1,402	$ (26,955)	(30,886)	(49,095)
Allowance for loan losses: Ending balance	306,116	371,521	306,116	371,521
Reserve for unfunded lending commitments: Beginning balance			29,334	29,907
Reserve for unfunded lending commitments: Provision for losses			4,134	961
Reserve for unfunded lending commitments: Ending balance	33,468	28,946	33,468	28,946
Total allowance for credit losses	339,584	400,467	339,584	400,467
Allowance for loan losses: Individually evaluated	516	835	516	835
Allowance for loan losses: Collectively evaluated	305,600	370,686	305,600	370,686
Reserve for unfunded lending commitments: Individually evaluated	3		3
Reserve for unfunded lending commitments: Collectively evaluated	33,465	28,946	33,465	28,946
Loans: Individually evaluated for impairment	7,806	22,076	7,806	22,076
Loans: Collectively evaluated for impairment	22,577,779	20,863,939	22,577,779	20,863,939
Loans receivable	22,585,585	20,886,015	22,585,585	20,886,015	$ 21,134,282
Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(17,947)	(44,681)
Allowance for loan losses: Recoveries			17,018	14,159
Allowance for loan losses: Net provision for loan losses			(35,020)	(48,134)
Total Commercial [Member] | Commercial Real Estate - Income Producing [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			108,058	109,474
Allowance for loan losses: Ending balance	77,412	121,095	77,412	121,095
Reserve for unfunded lending commitments: Beginning balance			1,694	1,099
Reserve for unfunded lending commitments: Provision for losses			205	124
Reserve for unfunded lending commitments: Ending balance	1,489	1,223	1,489	1,223
Total allowance for credit losses	78,901	122,318	78,901	122,318
Allowance for loan losses: Individually evaluated	17	20	17	20
Allowance for loan losses: Collectively evaluated	77,395	121,075	77,395	121,075
Reserve for unfunded lending commitments: Collectively evaluated	1,489	1,223	1,489	1,223
Loans: Individually evaluated for impairment	1,270	4,004	1,270	4,004
Loans: Collectively evaluated for impairment	3,685,270	3,463,935	3,685,270	3,463,935
Loans receivable	3,686,540	3,467,939	3,686,540	3,467,939	3,464,626
Total Commercial [Member] | Construction and Land Development [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			22,102	26,462
Allowance for loan losses: Ending balance	26,747	22,576	26,747	22,576
Reserve for unfunded lending commitments: Beginning balance			21,907	22,694
Reserve for unfunded lending commitments: Provision for losses			3,602	(383)
Reserve for unfunded lending commitments: Ending balance	25,509	22,311	25,509	22,311
Total allowance for credit losses	52,256	44,887	52,256	44,887
Allowance for loan losses: Individually evaluated	19	20	19	20
Allowance for loan losses: Collectively evaluated	26,728	22,556	26,728	22,556
Reserve for unfunded lending commitments: Collectively evaluated	25,509	22,311	25,509	22,311
Loans: Individually evaluated for impairment	118	127	118	127
Loans: Collectively evaluated for impairment	1,541,139	1,213,864	1,541,139	1,213,864
Loans receivable	1,541,257	1,213,991	1,541,257	1,213,991	1,228,670
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			(1,066)	(231)
Allowance for loan losses: Recoveries			878	100
Allowance for loan losses: Net provision for loan losses			(30,458)	11,752
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			(3)	(267)
Allowance for loan losses: Recoveries			132	1,548
Allowance for loan losses: Net provision for loan losses			(4,516)	(5,167)
Total Commercial [Member] | Total Commercial And Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			149,321	218,827
Allowance for loan losses: Ending balance	142,823	163,442	142,823	163,442
Reserve for unfunded lending commitments: Beginning balance			4,845	4,910
Reserve for unfunded lending commitments: Provision for losses			(248)	307
Reserve for unfunded lending commitments: Ending balance	5,093	4,603	5,093	4,603
Total allowance for credit losses	147,916	168,045	147,916	168,045
Allowance for loan losses: Individually evaluated	102	146	102	146
Allowance for loan losses: Collectively evaluated	142,721	163,296	142,721	163,296
Reserve for unfunded lending commitments: Individually evaluated	3		3
Reserve for unfunded lending commitments: Collectively evaluated	5,090	4,603	5,090	4,603
Loans: Individually evaluated for impairment	2,211	11,547	2,211	11,547
Loans: Collectively evaluated for impairment	12,936,349	12,218,369	12,936,349	12,218,369
Loans receivable	12,938,560	12,229,916	12,938,560	12,229,916	12,433,706
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			95,888	149,693
Allowance for loan losses: Ending balance	94,806	106,309	94,806	106,309
Reserve for unfunded lending commitments: Beginning balance			4,522	4,529
Reserve for unfunded lending commitments: Provision for losses			(238)	176
Reserve for unfunded lending commitments: Ending balance	4,760	4,353	4,760	4,353
Total allowance for credit losses	99,566	110,662	99,566	110,662
Allowance for loan losses: Individually evaluated	71	113	71	113
Allowance for loan losses: Collectively evaluated	94,735	106,196	94,735	106,196
Reserve for unfunded lending commitments: Individually evaluated	3		3
Reserve for unfunded lending commitments: Collectively evaluated	4,757	4,353	4,757	4,353
Loans: Individually evaluated for impairment	1,282	5,929	1,282	5,929
Loans: Collectively evaluated for impairment	9,904,145	9,411,061	9,904,145	9,411,061
Loans receivable	9,905,427	9,416,990	9,905,427	9,416,990	9,612,460
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			53,433	69,134
Allowance for loan losses: Ending balance	48,017	57,133	48,017	57,133
Reserve for unfunded lending commitments: Beginning balance			323	381
Reserve for unfunded lending commitments: Provision for losses			10	131
Reserve for unfunded lending commitments: Ending balance	333	250	333	250
Total allowance for credit losses	48,350	57,383	48,350	57,383
Allowance for loan losses: Individually evaluated	31	33	31	33
Allowance for loan losses: Collectively evaluated	47,986	57,100	47,986	57,100
Reserve for unfunded lending commitments: Collectively evaluated	333	250	333	250
Loans: Individually evaluated for impairment	929	5,618	929	5,618
Loans: Collectively evaluated for impairment	3,032,204	2,807,308	3,032,204	2,807,308
Loans receivable	3,033,133	2,812,926	3,033,133	2,812,926	2,821,246
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			(7,312)	(34,091)
Allowance for loan losses: Recoveries			10,066	6,942
Allowance for loan losses: Net provision for loan losses			(9,252)	(28,236)
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			(6,366)	(32,369)
Allowance for loan losses: Recoveries			9,460	6,579
Allowance for loan losses: Net provision for loan losses			(4,176)	(17,594)
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)	(1,722)
Allowance for loan losses: Recoveries			606	363
Allowance for loan losses: Net provision for loan losses			(5,076)	(10,642)
Residential Mortgages [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			30,623	48,842
Allowance for loan losses: Ending balance	30,947	31,073	30,947	31,073
Reserve for unfunded lending commitments: Beginning balance			22	19
Reserve for unfunded lending commitments: Provision for losses			(5)	8
Reserve for unfunded lending commitments: Ending balance	17	11	17	11
Total allowance for credit losses	30,964	31,084	30,964	31,084
Allowance for loan losses: Individually evaluated	276	447	276	447
Allowance for loan losses: Collectively evaluated	30,671	30,626	30,671	30,626
Reserve for unfunded lending commitments: Collectively evaluated	17	11	17	11
Loans: Individually evaluated for impairment	3,680	5,083	3,680	5,083
Loans: Collectively evaluated for impairment	2,840,043	2,345,970	2,840,043	2,345,970
Loans receivable	2,843,723	2,351,053	2,843,723	2,351,053	2,423,890
Residential Mortgages [Member] | Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(102)	(218)
Allowance for loan losses: Recoveries			1,463	933
Allowance for loan losses: Net provision for loan losses			(1,037)	(18,484)
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Beginning balance			31,961	46,572
Allowance for loan losses: Ending balance	28,187	33,335	28,187	33,335
Reserve for unfunded lending commitments: Beginning balance			866	1,185
Reserve for unfunded lending commitments: Provision for losses			494	387
Reserve for unfunded lending commitments: Ending balance	1,360	798	1,360	798
Total allowance for credit losses	29,547	34,133	29,547	34,133
Allowance for loan losses: Individually evaluated	102	202	102	202
Allowance for loan losses: Collectively evaluated	28,085	33,133	28,085	33,133
Reserve for unfunded lending commitments: Collectively evaluated	1,360	798	1,360	798
Loans: Individually evaluated for impairment	527	1,315	527	1,315
Loans: Collectively evaluated for impairment	1,574,978	1,621,801	1,574,978	1,621,801
Loans receivable	$ 1,575,505	$ 1,623,116	1,575,505	1,623,116	$ 1,583,390
Consumer [Member] | Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(9,464)	(9,874)
Allowance for loan losses: Recoveries			4,479	4,636
Allowance for loan losses: Net provision for loan losses			$ (1,211)	$ 7,999