Non-performing Assets and Impaired Loans - Loans by Credit Grades (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Total	$ 1,745,340	$ 1,377,472
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	802,792	673,059
Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	268,281	228,380
Commercial [Member] | Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	326,399	297,299
Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	5,018	2,027
Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	18,183	12,097
Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	184,911	133,256
Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	579,367	383,182
Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	414,924	242,521
Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	19,751	11,505
Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	144,692	129,156
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	363,181	321,231
Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	54,341	40,137
Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	153	219
Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	151,523	141,868
Consumer [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	157,164	139,007
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 1,713,981	$ 1,335,853
Percentage of total loans	98.20%	96.98%
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 781,108	$ 642,026
Pass [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	257,181	215,874
Pass [Member] | Commercial [Member] | Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	320,216	283,518
Pass [Member] | Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	5,018	2,027
Pass [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	18,112	12,018
Pass [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	180,581	128,589
Pass [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	573,130	377,288
Pass [Member] | Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	408,937	236,893
Pass [Member] | Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	19,501	11,239
Pass [Member] | Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	144,692	129,156
Pass [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	359,743	316,538
Pass [Member] | Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	53,800	39,900
Pass [Member] | Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	153	219
Pass [Member] | Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	150,895	141,264
Pass [Member] | Consumer [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	154,895	135,155
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 6,232	$ 13,959
Percentage of total loans	0.36%	1.01%
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 6,232	$ 13,959
Special Mention [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	4,954	7,623
Special Mention [Member] | Commercial [Member] | Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	585	4,458
Special Mention [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total		79
Special Mention [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	693	1,799
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 25,127	$ 27,661
Percentage of total loans	1.44%	2.01%
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 15,452	$ 17,074
Substandard [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,146	4,883
Substandard [Member] | Commercial [Member] | Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	5,598	9,323
Substandard [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	71
Substandard [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,637	2,868
Substandard [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,237	5,894
Substandard [Member] | Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	5,987	5,628
Substandard [Member] | Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	250	266
Substandard [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,438	4,693
Substandard [Member] | Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	541	237
Substandard [Member] | Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	628	604
Substandard [Member] | Consumer [Member] | Home Equity Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 2,269	$ 3,852
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Percentage of total loans	0.00%	0.00%