Loans and Leases - Summary of Major Loan and Lease Categories (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	$ 3,452,581	$ 3,081,287
Total Loans and Leases Held for Investment, Acquired	413,588	538,780
Total Loans and Leases Held for Investment	3,866,169	3,620,067	$ 3,487,164
Unearned Lease Income, Originated	(15,079)	(14,243)
Unearned Lease Income, Acquired	0	0
Unearned lease income, included in the above table	(15,079)	(14,243)
Net deferred costs, Originated	4,064	4,669
Net deferred costs, Acquired	0	0
Net deferred costs, included in the above table	4,064	4,669
Overdraft Deposits, Originated	156	222
Overdraft Deposits, Acquired	0	0
Overdraft deposits included in the above table	156	222
Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	867,636	833,100
Total Loans and Leases Held for Investment, Acquired	26,686	63,111
Total Loans and Leases Held for Investment	894,322	896,211	859,217
Real Estate-Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	1,442,681	1,235,681
Total Loans and Leases Held for Investment, Acquired	254,462	306,460
Total Loans and Leases Held for Investment	1,697,143	1,542,141
Real Estate-Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	188,895	171,244
Total Loans and Leases Held for Investment, Acquired	3,742	4,592
Total Loans and Leases Held for Investment	192,637	175,836
Real Estate-Residential Secured for Business Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	279,800	250,800
Total Loans and Leases Held for Investment, Acquired	66,531	91,167
Total Loans and Leases Held for Investment	346,331	341,967	310,020
Real Estate Residential Secured For Personal Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	327,833	260,654
Total Loans and Leases Held for Investment, Acquired	52,676	60,920
Total Loans and Leases Held for Investment	380,509	321,574
Real Estate-Home Equity Secured for Personal Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	177,632	171,884
Total Loans and Leases Held for Investment, Acquired	9,349	12,386
Total Loans and Leases Held for Investment	186,981	184,270
Loans to Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	32,096	28,156
Total Loans and Leases Held for Investment, Acquired	142	144
Total Loans and Leases Held for Investment	32,238	28,300	27,441
Lease Financings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	136,008	129,768
Total Loans and Leases Held for Investment, Acquired	0	0
Total Loans and Leases Held for Investment	$ 136,008	$ 129,768	$ 124,138