Loans and Allowance for Credit Losses (Allowance for Credit Losses by Portfolio Class) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 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	$ (9,761)	$ (17,229)	(32,288)	(22,140)
Allowance for loan losses: Ending balance	308,175	399,668	308,175	399,668
Reserve for unfunded lending commitments: Beginning balance			29,334	29,907
Reserve for unfunded lending commitments: Provision for losses			1,969	383
Reserve for unfunded lending commitments: Ending balance	31,303	29,524	31,303	29,524
Total allowance for credit losses	339,478	429,192	339,478	429,192
Allowance for loan losses: Individually evaluated	636	4,027	636	4,027
Allowance for loan losses: Collectively evaluated	307,539	395,641	307,539	395,641
Reserve for unfunded lending commitments: Individually evaluated		241		241
Reserve for unfunded lending commitments: Collectively evaluated	31,303	29,283	31,303	29,283
Loans: Individually evaluated for impairment	8,801	33,878	8,801	33,878
Loans: Collectively evaluated for impairment	21,837,267	21,114,652	21,837,267	21,114,652
Loans receivable	21,846,068	21,148,530	21,846,068	21,148,530	$ 21,134,282
Non-Purchased Credit Impaired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Allowance for loan losses: Charge-offs			(11,360)	(37,926)
Allowance for loan losses: Recoveries			11,727	9,174
Allowance for loan losses: Net provision for loan losses			(34,257)	(21,757)
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	82,951	123,780	82,951	123,780
Reserve for unfunded lending commitments: Beginning balance			1,694	1,099
Reserve for unfunded lending commitments: Provision for losses			274	244
Reserve for unfunded lending commitments: Ending balance	1,420	1,343	1,420	1,343
Total allowance for credit losses	84,371	125,123	84,371	125,123
Allowance for loan losses: Individually evaluated	18	21	18	21
Allowance for loan losses: Collectively evaluated	82,933	123,759	82,933	123,759
Reserve for unfunded lending commitments: Collectively evaluated	1,420	1,343	1,420	1,343
Loans: Individually evaluated for impairment	1,289	4,018	1,289	4,018
Loans: Collectively evaluated for impairment	3,639,954	3,415,010	3,639,954	3,415,010
Loans receivable	3,641,243	3,419,028	3,641,243	3,419,028	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	24,703	26,728	24,703	26,728
Reserve for unfunded lending commitments: Beginning balance			21,907	22,694
Reserve for unfunded lending commitments: Provision for losses			1,598	(1,470)
Reserve for unfunded lending commitments: Ending balance	23,505	21,224	23,505	21,224
Total allowance for credit losses	48,208	47,952	48,208	47,952
Allowance for loan losses: Individually evaluated	19	21	19	21
Allowance for loan losses: Collectively evaluated	24,684	26,707	24,684	26,707
Reserve for unfunded lending commitments: Collectively evaluated	23,505	21,224	23,505	21,224
Loans: Individually evaluated for impairment	120	129	120	129
Loans: Collectively evaluated for impairment	1,408,607	1,294,907	1,408,607	1,294,907
Loans receivable	1,408,727	1,295,036	1,408,727	1,295,036	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
Allowance for loan losses: Net provision for loan losses			(24,919)	14,537
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)	(256)
Allowance for loan losses: Recoveries			126	1,164
Allowance for loan losses: Net provision for loan losses			(2,478)	(642)
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	142,434	174,295	142,434	174,295
Reserve for unfunded lending commitments: Beginning balance			4,845	4,910
Reserve for unfunded lending commitments: Provision for losses			(91)	1,101
Reserve for unfunded lending commitments: Ending balance	4,936	6,011	4,936	6,011
Total allowance for credit losses	147,370	180,306	147,370	180,306
Allowance for loan losses: Individually evaluated	107	3,344	107	3,344
Allowance for loan losses: Collectively evaluated	142,327	170,951	142,327	170,951
Reserve for unfunded lending commitments: Individually evaluated		241		241
Reserve for unfunded lending commitments: Collectively evaluated	4,936	5,770	4,936	5,770
Loans: Individually evaluated for impairment	2,496	20,721	2,496	20,721
Loans: Collectively evaluated for impairment	12,607,070	12,321,857	12,607,070	12,321,857
Loans receivable	12,609,566	12,342,578	12,609,566	12,342,578	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	92,819	112,523	92,819	112,523
Reserve for unfunded lending commitments: Beginning balance			4,522	4,529
Reserve for unfunded lending commitments: Provision for losses			(51)	1,174
Reserve for unfunded lending commitments: Ending balance	4,573	5,703	4,573	5,703
Total allowance for credit losses	97,392	118,226	97,392	118,226
Allowance for loan losses: Individually evaluated	76	2,675	76	2,675
Allowance for loan losses: Collectively evaluated	92,743	109,848	92,743	109,848
Reserve for unfunded lending commitments: Individually evaluated		241		241
Reserve for unfunded lending commitments: Collectively evaluated	4,573	5,462	4,573	5,462
Loans: Individually evaluated for impairment	1,559	13,642	1,559	13,642
Loans: Collectively evaluated for impairment	9,643,533	9,519,068	9,643,533	9,519,068
Loans receivable	9,645,092	9,532,710	9,645,092	9,532,710	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	49,615	61,772	49,615	61,772
Reserve for unfunded lending commitments: Beginning balance			323	381
Reserve for unfunded lending commitments: Provision for losses			40	73
Reserve for unfunded lending commitments: Ending balance	363	308	363	308
Total allowance for credit losses	49,978	62,080	49,978	62,080
Allowance for loan losses: Individually evaluated	31	669	31	669
Allowance for loan losses: Collectively evaluated	49,584	61,103	49,584	61,103
Reserve for unfunded lending commitments: Collectively evaluated	363	308	363	308
Loans: Individually evaluated for impairment	937	7,079	937	7,079
Loans: Collectively evaluated for impairment	2,963,537	2,802,789	2,963,537	2,802,789
Loans receivable	2,964,474	2,809,868	2,964,474	2,809,868	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			(4,604)	(30,614)
Allowance for loan losses: Recoveries			7,094	4,474
Allowance for loan losses: Net provision for loan losses			(9,377)	(18,392)
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			(3,747)	(28,932)
Allowance for loan losses: Recoveries			6,603	4,187
Allowance for loan losses: Net provision for loan losses			(5,925)	(12,425)
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			(857)	(1,682)
Allowance for loan losses: Recoveries			491	287
Allowance for loan losses: Net provision for loan losses			(3,452)	(5,967)
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	28,584	36,465	28,584	36,465
Reserve for unfunded lending commitments: Beginning balance			22	19
Reserve for unfunded lending commitments: Provision for losses			(2)	6
Reserve for unfunded lending commitments: Ending balance	24	13	24	13
Total allowance for credit losses	28,608	36,478	28,608	36,478
Allowance for loan losses: Individually evaluated	322	437	322	437
Allowance for loan losses: Collectively evaluated	28,262	36,028	28,262	36,028
Reserve for unfunded lending commitments: Collectively evaluated	24	13	24	13
Loans: Individually evaluated for impairment	3,991	6,347	3,991	6,347
Loans: Collectively evaluated for impairment	2,611,816	2,406,112	2,611,816	2,406,112
Loans receivable	2,615,807	2,412,459	2,615,807	2,412,459	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			(60)	(207)
Allowance for loan losses: Recoveries			527	437
Allowance for loan losses: Net provision for loan losses			(2,506)	(12,607)
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	29,503	38,400	29,503	38,400
Reserve for unfunded lending commitments: Beginning balance			866	1,185
Reserve for unfunded lending commitments: Provision for losses			552	252
Reserve for unfunded lending commitments: Ending balance	1,418	933	1,418	933
Total allowance for credit losses	30,921	39,333	30,921	39,333
Allowance for loan losses: Individually evaluated	170	204	170	204
Allowance for loan losses: Collectively evaluated	29,333	38,196	29,333	38,196
Reserve for unfunded lending commitments: Collectively evaluated	1,418	933	1,418	933
Loans: Individually evaluated for impairment	905	2,663	905	2,663
Loans: Collectively evaluated for impairment	1,569,820	1,676,766	1,569,820	1,676,766
Loans receivable	$ 1,570,725	$ 1,679,429	1,570,725	1,679,429	$ 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			(5,627)	(6,618)
Allowance for loan losses: Recoveries			3,102	3,099
Allowance for loan losses: Net provision for loan losses			$ (67)	$ 4,653