Loans - Past Due Financing Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Current	$ 5,163,098	$ 4,775,965
Nonaccrual	26,955	26,476
Total financing receivables	5,198,404	4,825,214
Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	7,259	19,607
Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	984	2,640
Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	108	526
Real Estate | Construction and land development
Financing Receivable, Past Due [Line Items]
Total financing receivables	325,113	443,568
Real Estate | Commercial real estate
Financing Receivable, Past Due [Line Items]
Total financing receivables	2,378,971	2,132,066
Real Estate | Residential real estate
Financing Receivable, Past Due [Line Items]
Total financing receivables	1,507,863	1,324,377
Commercial and financial | Commercial and financial
Financing Receivable, Past Due [Line Items]
Total financing receivables	778,252	722,322
Consumer | Consumer
Financing Receivable, Past Due [Line Items]
Total financing receivables	208,205	202,881
Portfolio Loans
Financing Receivable, Past Due [Line Items]
Current	4,290,227	3,557,127
Nonaccrual	20,990	15,783
Total financing receivables	4,317,918	3,588,251
Portfolio Loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	6,040	12,296
Portfolio Loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	553	2,609
Portfolio Loans | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	108	436
Portfolio Loans | Real Estate | Construction and land development
Financing Receivable, Past Due [Line Items]
Current	276,984	301,348
Nonaccrual	4,351	28
Total financing receivables	281,335	301,473
Portfolio Loans | Real Estate | Construction and land development | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	97
Portfolio Loans | Real Estate | Construction and land development | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
Portfolio Loans | Real Estate | Construction and land development | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
Portfolio Loans | Real Estate | Commercial real estate
Financing Receivable, Past Due [Line Items]
Current	1,828,629	1,427,413
Nonaccrual	4,356	6,486
Total financing receivables	1,834,811	1,437,989
Portfolio Loans | Real Estate | Commercial real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	1,606	3,852
Portfolio Loans | Real Estate | Commercial real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	220	97
Portfolio Loans | Real Estate | Commercial real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	141
Portfolio Loans | Real Estate | Residential real estate
Financing Receivable, Past Due [Line Items]
Current	1,294,778	1,044,375
Nonaccrual	7,945	7,806
Total financing receivables	1,304,305	1,055,525
Portfolio Loans | Real Estate | Residential real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	1,564	2,524
Portfolio Loans | Real Estate | Residential real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	18	525
Portfolio Loans | Real Estate | Residential real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	295
Portfolio Loans | Commercial and financial | Commercial and financial
Financing Receivable, Past Due [Line Items]
Current	690,412	594,930
Nonaccrual	4,228	1,280
Total financing receivables	697,301	603,057
Portfolio Loans | Commercial and financial | Commercial and financial | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	2,553	5,186
Portfolio Loans | Commercial and financial | Commercial and financial | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	1,661
Portfolio Loans | Commercial and financial | Commercial and financial | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	108	0
Portfolio Loans | Consumer | Consumer
Financing Receivable, Past Due [Line Items]
Current	199,424	189,061
Nonaccrual	110	183
Total financing receivables	200,166	190,207
Portfolio Loans | Consumer | Consumer | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	317	637
Portfolio Loans | Consumer | Consumer | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	315	326
Portfolio Loans | Consumer | Consumer | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PULs
Financing Receivable, Past Due [Line Items]
Current	862,272	1,209,670
Nonaccrual	3,898	7,096
Total financing receivables	867,820	1,222,529
PULs | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	1,219	5,642
PULs | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	431	31
PULs | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	90
PULs | Real Estate | Construction and land development
Financing Receivable, Past Due [Line Items]
Current	43,044	140,013
Nonaccrual	574	0
Total financing receivables	43,618	141,944
PULs | Real Estate | Construction and land development | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	1,931
PULs | Real Estate | Construction and land development | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PULs | Real Estate | Construction and land development | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PULs | Real Estate | Commercial real estate
Financing Receivable, Past Due [Line Items]
Current	531,325	680,060
Nonaccrual	1,245	1,343
Total financing receivables	533,943	683,249
PULs | Real Estate | Commercial real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	942	1,846
PULs | Real Estate | Commercial real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	431	0
PULs | Real Estate | Commercial real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PULs | Real Estate | Residential real estate
Financing Receivable, Past Due [Line Items]
Current	201,159	260,781
Nonaccrual	412	3,740
Total financing receivables	201,848	266,134
PULs | Real Estate | Residential real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	277	1,523
PULs | Real Estate | Residential real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PULs | Real Estate | Residential real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	90
PULs | Commercial and financial | Commercial and financial
Financing Receivable, Past Due [Line Items]
Current	78,705	116,173
Nonaccrual	1,667	2,013
Total financing receivables	80,372	118,528
PULs | Commercial and financial | Commercial and financial | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	342
PULs | Commercial and financial | Commercial and financial | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PULs | Commercial and financial | Commercial and financial | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PULs | Consumer | Consumer
Financing Receivable, Past Due [Line Items]
Current	8,039	12,643
Nonaccrual	0	0
Total financing receivables	8,039	12,674
PULs | Consumer | Consumer | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PULs | Consumer | Consumer | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	31
PULs | Consumer | Consumer | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans
Financing Receivable, Past Due [Line Items]
Current	10,599	9,168
Nonaccrual	2,067	3,597
Total financing receivables	12,666	14,434
PCI Loans | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	1,669
PCI Loans | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Real Estate | Construction and land development
Financing Receivable, Past Due [Line Items]
Current	148	135
Nonaccrual	12	16
Total financing receivables	160	151
PCI Loans | Real Estate | Construction and land development | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Real Estate | Construction and land development | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Real Estate | Construction and land development | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Real Estate | Commercial real estate
Financing Receivable, Past Due [Line Items]
Current	9,298	8,403
Nonaccrual	919	1,391
Total financing receivables	10,217	10,828
PCI Loans | Real Estate | Commercial real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	1,034
PCI Loans | Real Estate | Commercial real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Real Estate | Commercial real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Real Estate | Residential real estate
Financing Receivable, Past Due [Line Items]
Current	587	556
Nonaccrual	1,123	2,162
Total financing receivables	1,710	2,718
PCI Loans | Real Estate | Residential real estate | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Real Estate | Residential real estate | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Real Estate | Residential real estate | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Commercial and financial | Commercial and financial
Financing Receivable, Past Due [Line Items]
Current	566	74
Nonaccrual	13	28
Total financing receivables	579	737
PCI Loans | Commercial and financial | Commercial and financial | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	635
PCI Loans | Commercial and financial | Commercial and financial | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Commercial and financial | Commercial and financial | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Consumer | Consumer
Financing Receivable, Past Due [Line Items]
Current	0	0
Nonaccrual	0	0
Total financing receivables	0	0
PCI Loans | Consumer | Consumer | Accruing 30-59 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Consumer | Consumer | Accruing 60-89 Days Past Due
Financing Receivable, Past Due [Line Items]
Financing receivables past due	0	0
PCI Loans | Consumer | Consumer | Accruing Greater Than 90 Days
Financing Receivable, Past Due [Line Items]
Financing receivables past due	$ 0	$ 0