Allowance for Loan and Lease Losses (Troubled Debt Restructuring) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) loans	Dec. 31, 2017 USD ($) loans	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	$ 156,130	$ 164,561
Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	$ 214,568	$ 211,867	$ 205,026	$ 189,904
Financing Receivable, Modifications, Number of Contracts | loans	491	632
Nonaccruing	$ 84,546	$ 92,534
Financing Receivable, Modifications, Recorded Investment	137,910	146,126
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 43,553	$ 49,000
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	164	204
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 13,318	$ 11,990
PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	9,144	10,026	13,769	16,312
Nonaccruing	1,300	624
Financing Receivable, Modifications, Recorded Investment	18,220	18,435
Commercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	74,560	95,392
Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,298	4,572
Commercial | Construction and land development | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	35,270	24,470	28,877	16,288
Nonaccruing	666	1,040
Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	61,065	78,221
Commercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	43,451	45,005	48,278	69,896
Nonaccruing	12,594	22,625
Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	860	1,800
Commercial | Other commercial real estate | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	2,481	4,571	3,269	2,168
Nonaccruing	366	916
Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	10,046	10,278
Commercial | Commercial and industrial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	55,620	59,824	56,132	48,640
Nonaccruing	4,624	4,876
Commercial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	291	521
Commercial | Other | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	2,221	4,689	3,127	1,855
Noncommercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	81,570	69,169
Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,337	0
Noncommercial | Construction and land development | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	2,350	3,962	1,596	1,485
Nonaccruing	1,823	1,989
Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	47,524	43,542
Noncommercial | Mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	15,472	15,706	14,447	14,105
Nonaccruing	35,662	38,942
Noncommercial | Other | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Nonaccruing	279	164
Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	28,688	22,853
Noncommercial | Revolving mortgage | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Allowance for loan and lease losses	21,862	22,436	$ 21,013	$ 15,971
Nonaccruing	25,563	19,990
Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	3,021	2,774
Performing Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	127,093	130,391
Performing Financial Instruments [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	64,171	76,300
Performing Financial Instruments [Member] | Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	1,946	4,089
Performing Financial Instruments [Member] | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	53,270	62,358
Performing Financial Instruments [Member] | Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	851	1,012
Performing Financial Instruments [Member] | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	7,986	8,320
Performing Financial Instruments [Member] | Commercial | Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	118	521
Performing Financial Instruments [Member] | Noncommercial
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	62,922	54,091
Performing Financial Instruments [Member] | Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,227	0
Performing Financial Instruments [Member] | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	37,903	34,067
Performing Financial Instruments [Member] | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	20,492	17,673
Performing Financial Instruments [Member] | Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Recorded Investment	2,300	2,351
Nonperforming Financial Instruments [Member]
Financing Receivable, Modifications [Line Items]
Nonaccruing	29,037	34,170
Nonperforming Financial Instruments [Member] | Commercial
Financing Receivable, Modifications [Line Items]
Nonaccruing	10,389	19,092
Nonperforming Financial Instruments [Member] | Commercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Nonaccruing	352	483
Nonperforming Financial Instruments [Member] | Commercial | Mortgage
Financing Receivable, Modifications [Line Items]
Nonaccruing	7,795	15,863
Nonperforming Financial Instruments [Member] | Commercial | Other commercial real estate
Financing Receivable, Modifications [Line Items]
Nonaccruing	9	788
Nonperforming Financial Instruments [Member] | Commercial | Commercial and industrial
Financing Receivable, Modifications [Line Items]
Nonaccruing	2,060	1,958
Nonperforming Financial Instruments [Member] | Commercial | Other
Financing Receivable, Modifications [Line Items]
Nonaccruing	173	0
Nonperforming Financial Instruments [Member] | Noncommercial
Financing Receivable, Modifications [Line Items]
Nonaccruing	18,648	15,078
Nonperforming Financial Instruments [Member] | Noncommercial | Construction and land development
Financing Receivable, Modifications [Line Items]
Nonaccruing	110	0
Nonperforming Financial Instruments [Member] | Noncommercial | Mortgage
Financing Receivable, Modifications [Line Items]
Nonaccruing	9,621	9,475
Nonperforming Financial Instruments [Member] | Noncommercial | Revolving mortgage
Financing Receivable, Modifications [Line Items]
Nonaccruing	8,196	5,180
Nonperforming Financial Instruments [Member] | Noncommercial | Consumer and Other
Financing Receivable, Modifications [Line Items]
Nonaccruing	$ 721	$ 423
Extended Maturity [Member] | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	42	47
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 5,486	$ 6,517
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	8	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 865	$ 273
Extended Maturity [Member] | Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	21	13
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 3,933	$ 3,007
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	4	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 675	$ 0
Extended Maturity [Member] | Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	21	34
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,554	$ 3,510
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	4	2
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 190	$ 273
Interest Rate Below Market Reduction [Member] | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	269	363
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 28,404	$ 30,412
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	92	110
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 8,459	$ 7,983
Interest Rate Below Market Reduction [Member] | Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	85	92
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 12,859	$ 14,811
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	24	32
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 2,998	$ 3,392
Interest Rate Below Market Reduction [Member] | Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	184	271
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 15,545	$ 15,601
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	68	78
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 5,461	$ 4,591
Discharge of Debt [Member] | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	177	216
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 8,660	$ 10,865
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	64	91
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 3,994	$ 3,100
Discharge of Debt [Member] | Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	26	39
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 2,043	$ 3,012
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	8	26
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 825	$ 708
Discharge of Debt [Member] | Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	151	177
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 6,617	$ 7,853
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	56	65
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 3,169	$ 2,392
Principal Forgiveness [Member] | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	3	6
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,003	$ 1,206
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 634
Principal Forgiveness [Member] | Commercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	3	5
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 1,003	$ 1,124
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 634
Principal Forgiveness [Member] | Noncommercial | Non-PCI Loans
Financing Receivable, Modifications [Line Items]
Financing Receivable, Modifications, Number of Contracts | loans	0	1
Financing Receivable, Modifications, Post-Modification Recorded Investment	$ 0	$ 82
Financing Receivable, Modifications, Subsequent Default, Number of Contracts | loans	0	0
Financing Receivable, Modifications, Subsequent Default, Recorded Investment	$ 0	$ 0