Loans - Risk Category, Class of Loans and Recorded Investment (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 3,897,125	$ 3,817,377
Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	374,244	343,125
Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,645,239	1,639,992
Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,065,152	1,038,810
Commercial and Financial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	616,702	606,014
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	195,788	189,436
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,799,349	3,722,027
Pass [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	363,778	328,127
Pass [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,596,893	1,586,932
Pass [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,036,786	1,023,925
Pass [Member] | Commercial and Financial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	608,025	593,689
Pass [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	193,867	189,354
Special mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	44,737	47,545
Special mention [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	8,471	10,414
Special mention [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	29,421	29,273
Special mention [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	2,456	4,621
Special mention [Member] | Commercial and Financial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,056	3,237
Special mention [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,333	0
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	51,485	47,494
Substandard [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,995	4,584
Substandard [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	18,925	23,787
Substandard [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	25,910	10,203
Substandard [Member] | Commercial and Financial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,067	8,838
Substandard [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	588	82
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,554	311
Doubtful [Member] | Construction & Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Doubtful [Member] | Commercial Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	0
Doubtful [Member] | Residential Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	61
Doubtful [Member] | Commercial and Financial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,554	250
Doubtful [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 0	$ 0