Loans - Risk Category, Class of Loans by Class of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Net Loans	$ 4,825,214	$ 3,817,377
Pass
Financing Receivable, Recorded Investment [Line Items]
Net Loans	4,694,297	3,722,027
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net Loans	67,296	47,545
Substandard
Financing Receivable, Recorded Investment [Line Items]
Net Loans	63,596	47,494
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net Loans	25	311
Real Estate | Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Net Loans	443,568	343,125
Real Estate | Construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Net Loans	428,044	328,127
Real Estate | Construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net Loans	10,429	10,414
Real Estate | Construction and land development | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net Loans	5,095	4,584
Real Estate | Construction and land development | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net Loans	0	0
Real Estate | Commercial real estate
Financing Receivable, Recorded Investment [Line Items]
Net Loans	2,132,066	1,639,992
Real Estate | Commercial real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Net Loans	2,063,589	1,586,932
Real Estate | Commercial real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net Loans	41,429	29,273
Real Estate | Commercial real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net Loans	27,048	23,787
Real Estate | Commercial real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net Loans	0	0
Real Estate | Residential real estate
Financing Receivable, Recorded Investment [Line Items]
Net Loans	1,324,377	1,038,810
Real Estate | Residential real estate | Pass
Financing Receivable, Recorded Investment [Line Items]
Net Loans	1,296,634	1,023,925
Real Estate | Residential real estate | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net Loans	3,654	4,621
Real Estate | Residential real estate | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net Loans	24,089	10,203
Real Estate | Residential real estate | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net Loans	0	61
Commercial and financial | Commercial and financial
Financing Receivable, Recorded Investment [Line Items]
Net Loans	722,322	606,014
Commercial and financial | Commercial and financial | Pass
Financing Receivable, Recorded Investment [Line Items]
Net Loans	707,663	593,689
Commercial and financial | Commercial and financial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net Loans	8,387	3,237
Commercial and financial | Commercial and financial | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net Loans	6,247	8,838
Commercial and financial | Commercial and financial | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net Loans	25	250
Consumer | Consumer
Financing Receivable, Recorded Investment [Line Items]
Net Loans	202,881	189,436
Consumer | Consumer | Pass
Financing Receivable, Recorded Investment [Line Items]
Net Loans	198,367	189,354
Consumer | Consumer | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Net Loans	3,397	0
Consumer | Consumer | Substandard
Financing Receivable, Recorded Investment [Line Items]
Net Loans	1,117	82
Consumer | Consumer | Doubtful
Financing Receivable, Recorded Investment [Line Items]
Net Loans	$ 0	$ 0