Loans and Leases - Summary of Major Loan and Lease Categories (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	$ 2,390,832	$ 1,883,563
Total Loans and Leases Held for Investment, Acquired	895,054	295,450
Total Loans and Leases Held for Investment	3,285,886	2,179,013
Unearned Lease Income, Originated	(15,970)	(13,829)
Unearned Lease Income, Acquired	0	0
Unearned lease income, included in the above table	(15,970)	(13,829)
Net deferred costs, Originated	4,503	4,244
Net deferred costs, Acquired	0	0
Net deferred costs, included in the above table	4,503	4,244
Overdraft Deposits, Originated	84	35
Overdraft Deposits, Acquired	0	0
Overdraft Deposits	84	35
Commercial, Financial and Agricultural [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	663,221	479,980
Total Loans and Leases Held for Investment, Acquired	160,045	24,535
Total Loans and Leases Held for Investment	823,266	504,515
Real Estate-Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	909,581	759,342
Total Loans and Leases Held for Investment, Acquired	465,368	126,550
Total Loans and Leases Held for Investment	1,374,949	885,892
Real Estate-Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	142,891	91,904
Total Loans and Leases Held for Investment, Acquired	31,953	4,637
Total Loans and Leases Held for Investment	174,844	96,541
Real Estate-Residential Secured for Business Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	151,931	94,280
Total Loans and Leases Held for Investment, Acquired	142,137	124,503
Total Loans and Leases Held for Investment	294,068	218,783
Real Estate-Residential Secured for Personal Purpose [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	210,377	177,850
Total Loans and Leases Held for Investment, Acquired	80,431	3,305
Total Loans and Leases Held for Investment	290,808	181,155
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	147,982	125,361
Total Loans and Leases Held for Investment, Acquired	14,857	11,594
Total Loans and Leases Held for Investment	162,839	136,955
Loans to Individuals [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	30,110	29,406
Total Loans and Leases Held for Investment, Acquired	263	326
Total Loans and Leases Held for Investment	30,373	29,732
Lease Financings [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment, Originated	134,739	125,440
Total Loans and Leases Held for Investment, Acquired	0	0
Total Loans and Leases Held for Investment	134,739	125,440
Real Estate-Commercial and Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total Loans and Leases Held for Investment	$ 1,549,793	$ 982,433