Non-performing Loans and Impaired Loans - Loans by Credit Grades (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Total	$ 1,319,828	$ 1,067,935
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	646,896	504,584
Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	206,000	156,262
Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	294,681	224,713
Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	835	400
Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	24,188	21,289
Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	121,192	101,920
Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	375,783	283,732
Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	225,819	176,068
Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	9,068	9,508
Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	140,896	98,156
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	297,149	279,619
Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	34,106	29,983
Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	256	294
Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	132,053	131,384
Consumer [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	130,734	117,958
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,270,226	1,019,365
Percentage of total loans	96.24%	95.45%
Pass [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	607,729	466,820
Pass [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	194,208	146,085
Pass [Member] | Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	273,976	208,625
Pass [Member] | Commercial [Member] | Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	835	400
Pass [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	22,941	19,858
Pass [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	115,769	91,852
Pass [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	369,111	277,586
Pass [Member] | Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	219,421	170,202
Pass [Member] | Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	8,794	9,228
Pass [Member] | Real Estate [Member] | Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	140,896	98,156
Pass [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	293,386	274,959
Pass [Member] | Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	33,735	29,781
Pass [Member] | Consumer [Member] | Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	256	294
Pass [Member] | Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	131,493	130,851
Pass [Member] | Consumer [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	127,902	114,033
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	14,107	13,861
Percentage of total loans	1.07%	1.30%
Special Mention [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	14,107	13,861
Special Mention [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	2,728	2,231
Special Mention [Member] | Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	9,516	5,047
Special Mention [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	85	91
Special Mention [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,778	6,492
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	35,495	34,709
Percentage of total loans	2.69%	3.25%
Substandard [Member] | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	25,060	23,903
Substandard [Member] | Commercial [Member] | Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	9,064	7,946
Substandard [Member] | Commercial [Member] | Non-owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	11,189	11,041
Substandard [Member] | Commercial [Member] | Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,162	1,340
Substandard [Member] | Commercial [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,645	3,576
Substandard [Member] | Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,672	6,146
Substandard [Member] | Real Estate [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,398	5,866
Substandard [Member] | Real Estate [Member] | Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	274	280
Substandard [Member] | Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,763	4,660
Substandard [Member] | Consumer [Member] | Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	371	202
Substandard [Member] | Consumer [Member] | Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	560	533
Substandard [Member] | Consumer [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 2,832	$ 3,925
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Percentage of total loans	0.00%	0.00%