Allowance for Loan Losses - Allowance for Loan Losses (Detail) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Balance at beginning of the period				$ 16,501				$ 16,501	$ 15,992	$ 18,270
Total loans charged-off								6,099	4,129	6,250
Total loan recoveries								970	1,580	2,052
Net loans charged-off (recovered)								5,129	2,549	4,198
Total provision charged to operating expense	$ 342	$ 300	$ 1,906	$ 614	$ 978	$ 1,741	$ 339	3,162	3,058	1,920
Balance at the end of the period	$ 14,534				$ 16,501			14,534	16,501	15,992
Commercial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								3,437	1,802	2,532
Total loan recoveries								192	773	668
Total provision charged to operating expense								2,531	2,277	756
Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								2,208	40	138
Total loan recoveries								104	13	65
Commercial [Member] | Non Owner Occupied Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								556	136	937
Total loan recoveries								1	210	71
Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off									173	182
Total loan recoveries								35	55
Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								673	1,453	1,275
Total loan recoveries								52	495	532
Real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								288	328	1,055
Total loan recoveries								69	21	114
Total provision charged to operating expense								62	(1,153)	1,132
Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								288	328	1,055
Total loan recoveries								69	21	114
Consumer [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								2,374	1,999	2,663
Total loan recoveries								709	786	1,270
Total provision charged to operating expense								569	1,934	32
Consumer [Member] | Direct Installment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								367	250	333
Total loan recoveries								106	67	488
Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								1,081	1,233	1,178
Total loan recoveries								489	560	658
Consumer [Member] | Home Equity Loan [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans charged-off								926	516	1,152
Total loan recoveries								$ 114	$ 159	$ 124