Allowance for Loan and Lease Losses (Troubled Debt Restructuring) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) loans	Dec. 31, 2018 USD ($) loans	Dec. 31, 2017 USD ($) loans	Sep. 30, 2019 USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 171,192	$ 156,130	$ 164,561
Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	154,000	137,900	146,100
Nonaccruing	114,946	84,546
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 52,169	$ 43,554	$ 49,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	190	164	204
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 19,709	$ 13,318	$ 11,990
PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	17,200	18,200	18,500
Nonaccruing		1,300		$ 6,700
Commercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	77,536	74,560	95,392
Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	42,407	18,529
Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,766	2,298	4,572
Commercial | Construction and land development | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	4,281	666
Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	61,935	61,065	78,221
Commercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	29,733	12,594
Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	571	860	1,800
Commercial | Other commercial real estate | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	708	366
Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	11,839	10,046	10,278
Commercial | Commercial and industrial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	7,365	4,624
Commercial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	425	291	521
Commercial | Other | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	320	279
Noncommercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	93,656	81,570	69,169
Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	72,539	66,017
Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	3,882	2,337	0
Noncommercial | Construction and land development | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	2,828	1,823
Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	57,861	47,524	43,542
Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	28,399	28,688	22,853
Noncommercial | Revolving mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	22,411	25,563
Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	3,514	3,021	2,774
Performing Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	128,750	127,093	130,391
Performing Financial Instruments [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	61,627	64,171	76,300
Performing Financial Instruments [Member] | Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	487	1,946	4,089
Performing Financial Instruments [Member] | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	50,819	53,270	62,358
Performing Financial Instruments [Member] | Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	571	851	1,012
Performing Financial Instruments [Member] | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	9,430	7,986	8,320
Performing Financial Instruments [Member] | Commercial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	320	118	521
Performing Financial Instruments [Member] | Noncommercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	67,123	62,922	54,091
Performing Financial Instruments [Member] | Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	1,452	2,227	0
Performing Financial Instruments [Member] | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	41,813	37,903	34,067
Performing Financial Instruments [Member] | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	21,032	20,492	17,673
Performing Financial Instruments [Member] | Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,826	2,300	2,351
Nonperforming Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Nonaccruing	42,442	29,037	34,170
Nonperforming Financial Instruments [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Nonaccruing	15,909	10,389	19,092
Nonperforming Financial Instruments [Member] | Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Nonaccruing	2,279	352	483
Nonperforming Financial Instruments [Member] | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Nonaccruing	11,116	7,795	15,863
Nonperforming Financial Instruments [Member] | Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Nonaccruing	0	9	788
Nonperforming Financial Instruments [Member] | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Nonaccruing	2,409	2,060	1,958
Nonperforming Financial Instruments [Member] | Commercial | Other
Financing Receivable, Modifications [Line Items]
Nonaccruing	105	173	0
Nonperforming Financial Instruments [Member] | Noncommercial
Financing Receivable, Modifications [Line Items]
Nonaccruing	26,533	18,648	15,078
Nonperforming Financial Instruments [Member] | Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Nonaccruing	2,430	110	0
Nonperforming Financial Instruments [Member] | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Nonaccruing	16,048	9,621	9,475
Nonperforming Financial Instruments [Member] | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Nonaccruing	7,367	8,196	5,180
Nonperforming Financial Instruments [Member] | Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Nonaccruing	688	721	423
Extended Maturity [Member] | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 4,246	$ 5,487	$ 6,517
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	6	8	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 839	$ 865	$ 273
Extended Maturity [Member] | Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 3,904	$ 3,933	$ 3,007
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	5	4	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 533	$ 675	$ 0
Extended Maturity [Member] | Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 342	$ 1,554	$ 3,510
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	1	4	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 306	$ 190	$ 273
Interest Rate Below Market Reduction [Member] | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 26,390	$ 28,404	$ 30,412
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	90	92	110
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 6,648	$ 8,459	$ 7,983
Interest Rate Below Market Reduction [Member] | Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 13,932	$ 12,859	$ 14,811
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	24	24	32
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 2,634	$ 2,998	$ 3,392
Interest Rate Below Market Reduction [Member] | Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 12,458	$ 15,545	$ 15,601
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	66	68	78
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 4,014	$ 5,461	$ 4,591
Discharge of Debt [Member] | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 15,920	$ 8,660	$ 10,865
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	91	64	91
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 9,267	$ 3,994	$ 3,100
Discharge of Debt [Member] | Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 5,571	$ 2,043	$ 3,012
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	20	8	26
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 5,028	$ 825	$ 708
Discharge of Debt [Member] | Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 10,349	$ 6,617	$ 7,853
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	71	56	65
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 4,239	$ 3,169	$ 2,392
Principal Forgiveness [Member] | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 5,613	$ 1,003	$ 1,206
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	3	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 2,955	$ 0	$ 634
Principal Forgiveness [Member] | Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,595	$ 1,003	$ 1,124
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	1	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 238	$ 0	$ 634
Principal Forgiveness [Member] | Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 4,018	$ 0	$ 82
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	2	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 2,717	$ 0	$ 0