Loans and Leases - Reserve for Loan and Lease Losses and Recorded Investment in Loans and Leases (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	$ 322	$ 998
Ending balance: collectively evaluated for impairment	17,298	19,664
Ending balance: acquired credit impaired loans evaluated for impairment	8
Total ending balance	17,628	20,662	$ 24,494	$ 24,746
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	48,933	56,191
Ending balance: collectively evaluated for impairment	1,834,630	1,570,434
Acquired non-credit impaired loans	294,197
Acquired credit impaired loans	1,253
Total Loans and Leases Held for Investment	2,179,013	1,626,625
Commercial, Financial and Agricultural [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	208	920
Ending balance: collectively evaluated for impairment	6,210	6,000
Ending balance: acquired credit impaired loans evaluated for impairment	0
Total ending balance	6,418	6,920	9,789	11,594
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	12,881	16,561
Ending balance: collectively evaluated for impairment	467,099	441,266
Acquired non-credit impaired loans	24,218
Acquired credit impaired loans	317
Total Loans and Leases Held for Investment	504,515	457,827
Real Estate-Commercial and Construction [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	0	78
Ending balance: collectively evaluated for impairment	6,564	8,865
Ending balance: acquired credit impaired loans evaluated for impairment	8
Total ending balance	6,572	8,943	8,780	7,507
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	30,088	35,926
Ending balance: collectively evaluated for impairment	821,158	672,439
Acquired non-credit impaired loans	130,674
Acquired credit impaired loans	513
Total Loans and Leases Held for Investment	982,433	708,365
Real Estate-Residential Secured for Business Purpose [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	45	0
Ending balance: collectively evaluated for impairment	718	763
Ending balance: acquired credit impaired loans evaluated for impairment	0
Total ending balance	763	763	1,062	639
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	4,892	3,008
Ending balance: collectively evaluated for impairment	89,388	33,924
Acquired non-credit impaired loans	124,080
Acquired credit impaired loans	423
Total Loans and Leases Held for Investment	218,783	36,932
Real Estate-Residential and Home Equity Secured for Personal Purpose [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	69	0
Ending balance: collectively evaluated for impairment	1,506	1,124
Ending balance: acquired credit impaired loans evaluated for impairment	0
Total ending balance	1,575	1,124	1,284	980
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	1,072	696
Ending balance: collectively evaluated for impairment	302,139	274,404
Acquired non-credit impaired loans	14,899
Acquired credit impaired loans	0
Total Loans and Leases Held for Investment	318,110	275,100
Loans to Individuals [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	346	360
Ending balance: acquired credit impaired loans evaluated for impairment	0
Total ending balance	346	360	694	679
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	29,406	29,941
Acquired non-credit impaired loans	326
Acquired credit impaired loans	0
Total Loans and Leases Held for Investment	29,732	29,941
Lease Financings [Member]
Reserve for loan and lease losses:
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	1,042	985
Ending balance: acquired credit impaired loans evaluated for impairment	0
Total ending balance	1,042	985	1,285	1,326
Loans and leases held for investment:
Ending balance: individually evaluated for impairment	0	0
Ending balance: collectively evaluated for impairment	125,440	118,460
Acquired non-credit impaired loans	0
Acquired credit impaired loans	0
Total Loans and Leases Held for Investment	125,440	118,460
Unallocated [Member]
Reserve for loan and lease losses:
Ending balance: collectively evaluated for impairment	912	1,567
Ending balance: acquired credit impaired loans evaluated for impairment	0
Total ending balance	$ 912	$ 1,567	$ 1,600	$ 2,021