Loans and Leases - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	$ 5,306,841	$ 4,386,836
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		3,454,955
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		67,798
Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		71,285
Internally Assigned Grades [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		3,594,038
Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		788,650
Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		4,148
Performing and Nonperforming [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		792,798
Commercial, Financial and Agricultural [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	892,665	947,029
Commercial, Financial and Agricultural [Member] | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		911,848
Commercial, Financial and Agricultural [Member] | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		18,843
Commercial, Financial and Agricultural [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		16,338
Commercial, Financial and Agricultural [Member] | Internally Assigned Grades [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		947,029
Paycheck Protection Program Loans [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	483,773	0
Real Estate-Commercial [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	2,458,872	2,040,441
Real Estate-Commercial [Member] | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		1,974,561
Real Estate-Commercial [Member] | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		24,199
Real Estate-Commercial [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		41,681
Real Estate-Commercial [Member] | Internally Assigned Grades [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		2,040,441
Real Estate-Construction [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	243,355	232,595
Real Estate-Construction [Member] | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		201,424
Real Estate-Construction [Member] | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		20,987
Real Estate-Construction [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		10,184
Real Estate-Construction [Member] | Internally Assigned Grades [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		232,595
Real Estate-Residential Secured for Business Purpose [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	381,446	373,973
Real Estate-Residential Secured for Business Purpose [Member] | Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		367,122
Real Estate-Residential Secured for Business Purpose [Member] | Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		3,769
Real Estate-Residential Secured for Business Purpose [Member] | Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		3,082
Real Estate-Residential Secured for Business Purpose [Member] | Internally Assigned Grades [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		373,973
Real Estate-Residential Secured for Personal Purpose [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	487,600	439,059
Real Estate-Residential Secured for Personal Purpose [Member] | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		437,021
Real Estate-Residential Secured for Personal Purpose [Member] | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		2,038
Real Estate-Residential Secured for Personal Purpose [Member] | Performing and Nonperforming [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		439,059
Real Estate-Home Equity Secured for Personal Purpose [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	166,609	174,435
Real Estate-Home Equity Secured for Personal Purpose [Member] | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		172,954
Real Estate-Home Equity Secured for Personal Purpose [Member] | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		1,481
Real Estate-Home Equity Secured for Personal Purpose [Member] | Performing and Nonperforming [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		174,435
Loans to Individuals [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	27,482	29,883
Loans to Individuals [Member] | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		29,809
Loans to Individuals [Member] | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		74
Loans to Individuals [Member] | Performing and Nonperforming [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		29,883
Lease Financings [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment	$ 165,039	149,421
Lease Financings [Member] | Performing
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		148,866
Lease Financings [Member] | Nonperforming
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		555
Lease Financings [Member] | Performing and Nonperforming [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Loans and leases held for investment		$ 149,421