Loans - Past Due Financing Receivables (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Current	$ 4,847,799	$ 4,775,965
Nonaccrual	22,796	26,476
Total Financing Receivables	4,888,139	4,825,214
Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	10,475	19,607
Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	6,856	2,640
Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	213	526
Construction and land development
Financing Receivable, Past Due [Line Items]
Total Financing Receivables	379,991	443,568
Commercial real estate
Financing Receivable, Past Due [Line Items]
Total Financing Receivables	2,190,285	2,132,066
Residential real estate
Financing Receivable, Past Due [Line Items]
Total Financing Receivables	1,400,184	1,324,377
Commercial and financial
Financing Receivable, Past Due [Line Items]
Total Financing Receivables	701,747	722,322
Consumer
Financing Receivable, Past Due [Line Items]
Total Financing Receivables	215,932	202,881
Portfolio Loans
Financing Receivable, Past Due [Line Items]
Current	3,785,014	3,557,127
Nonaccrual	15,810	15,783
Total Financing Receivables	3,817,358	3,588,251
Portfolio Loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	9,922	12,296
Portfolio Loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	6,399	2,609
Portfolio Loans | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	213	436
Portfolio Loans | Construction and land development
Financing Receivable, Past Due [Line Items]
Current	295,828	301,348
Nonaccrual	26	28
Total Financing Receivables	300,182	301,473
Portfolio Loans | Construction and land development | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	97
Portfolio Loans | Construction and land development | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	4,328	0
Portfolio Loans | Construction and land development | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Portfolio Loans | Commercial real estate
Financing Receivable, Past Due [Line Items]
Current	1,543,584	1,427,413
Nonaccrual	5,919	6,486
Total Financing Receivables	1,552,024	1,437,989
Portfolio Loans | Commercial real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	1,098	3,852
Portfolio Loans | Commercial real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	1,423	97
Portfolio Loans | Commercial real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	141
Portfolio Loans | Residential real estate
Financing Receivable, Past Due [Line Items]
Current	1,143,397	1,044,375
Nonaccrual	7,747	7,806
Total Financing Receivables	1,153,951	1,055,525
Portfolio Loans | Residential real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	2,686	2,524
Portfolio Loans | Residential real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	121	525
Portfolio Loans | Residential real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	295
Portfolio Loans | Commercial and financial
Financing Receivable, Past Due [Line Items]
Current	597,048	594,930
Nonaccrual	2,032	1,280
Total Financing Receivables	605,237	603,057
Portfolio Loans | Commercial and financial | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	5,764	5,186
Portfolio Loans | Commercial and financial | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	221	1,661
Portfolio Loans | Commercial and financial | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	172	0
Portfolio Loans | Consumer
Financing Receivable, Past Due [Line Items]
Current	205,157	189,061
Nonaccrual	86	183
Total Financing Receivables	205,964	190,207
Portfolio Loans | Consumer | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	374	637
Portfolio Loans | Consumer | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	306	326
Portfolio Loans | Consumer | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	41	0
PULs
Financing Receivable, Past Due [Line Items]
Current	1,052,112	1,209,670
Nonaccrual	4,078	7,096
Total Financing Receivables	1,057,200	1,222,529
PULs | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	553	5,642
PULs | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	457	31
PULs | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	90
PULs | Construction and land development
Financing Receivable, Past Due [Line Items]
Current	78,693	140,013
Nonaccrual	574	0
Total Financing Receivables	79,654	141,944
PULs | Construction and land development | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	387	1,931
PULs | Construction and land development | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
PULs | Construction and land development | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
PULs | Commercial real estate
Financing Receivable, Past Due [Line Items]
Current	625,472	680,060
Nonaccrual	1,973	1,343
Total Financing Receivables	627,937	683,249
PULs | Commercial real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	166	1,846
PULs | Commercial real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	326	0
PULs | Commercial real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
PULs | Residential real estate
Financing Receivable, Past Due [Line Items]
Current	242,698	260,781
Nonaccrual	936	3,740
Total Financing Receivables	243,765	266,134
PULs | Residential real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	1,523
PULs | Residential real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	131	0
PULs | Residential real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	90
PULs | Commercial and financial
Financing Receivable, Past Due [Line Items]
Current	95,311	116,173
Nonaccrual	565	2,013
Total Financing Receivables	95,876	118,528
PULs | Commercial and financial | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	342
PULs | Commercial and financial | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
PULs | Commercial and financial | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
PULs | Consumer
Financing Receivable, Past Due [Line Items]
Current	9,938	12,643
Nonaccrual	30	0
Total Financing Receivables	9,968	12,674
PULs | Consumer | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
PULs | Consumer | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	31
PULs | Consumer | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans
Financing Receivable, Past Due [Line Items]
Current	10,673	9,168
Nonaccrual	2,908	3,597
Total Financing Receivables	13,581	14,434
Purchased Credit Impaired Loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	1,669
Purchased Credit Impaired Loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Construction and land development
Financing Receivable, Past Due [Line Items]
Current	141	135
Nonaccrual	14	16
Total Financing Receivables	155	151
Purchased Credit Impaired Loans | Construction and land development | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Construction and land development | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Construction and land development | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Commercial real estate
Financing Receivable, Past Due [Line Items]
Current	9,353	8,403
Nonaccrual	971	1,391
Total Financing Receivables	10,324	10,828
Purchased Credit Impaired Loans | Commercial real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	1,034
Purchased Credit Impaired Loans | Commercial real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Commercial real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Residential real estate
Financing Receivable, Past Due [Line Items]
Current	562	556
Nonaccrual	1,906	2,162
Total Financing Receivables	2,468	2,718
Purchased Credit Impaired Loans | Residential real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Residential real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Residential real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Commercial and financial
Financing Receivable, Past Due [Line Items]
Current	617	74
Nonaccrual	17	28
Total Financing Receivables	634	737
Purchased Credit Impaired Loans | Commercial and financial | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	635
Purchased Credit Impaired Loans | Commercial and financial | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Commercial and financial | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Consumer
Financing Receivable, Past Due [Line Items]
Current	0	0
Nonaccrual	0	0
Total Financing Receivables	0	0
Purchased Credit Impaired Loans | Consumer | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Consumer | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	0	0
Purchased Credit Impaired Loans | Consumer | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivable, recorded investment, past due	$ 0	$ 0