Non-performing Loans and Impaired Loans - Loans by Credit Grades (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Total	$ 1,341,550	$ 1,067,935
Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	676,022	504,584
Commercial [Member] \| Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	233,069	156,262
Commercial [Member] \| Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	298,408	224,713
Commercial [Member] \| Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,289	400
Commercial [Member] \| Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	12,574	21,289
Commercial [Member] \| Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	130,682	101,920
Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	356,244	283,732
Real Estate [Member] \| Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	239,989	176,068
Real Estate [Member] \| Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	11,122	9,508
Real Estate [Member] \| Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	105,133	98,156
Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	309,284	279,619
Consumer [Member] \| Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	36,720	29,983
Consumer [Member] \| Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	236	294
Consumer [Member] \| Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	139,138	131,384
Consumer [Member] \| Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	133,190	117,958
Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,298,289	1,019,365
Percentage of total loans	96.78%	95.45%
Pass [Member] \| Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	637,798	466,820
Pass [Member] \| Commercial [Member] \| Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	221,514	146,085
Pass [Member] \| Commercial [Member] \| Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	278,452	208,625
Pass [Member] \| Commercial [Member] \| Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,030	400
Pass [Member] \| Commercial [Member] \| Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	11,379	19,858
Pass [Member] \| Commercial [Member] \| Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	125,423	91,852
Pass [Member] \| Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	353,773	277,586
Pass [Member] \| Real Estate [Member] \| Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	237,518	170,202
Pass [Member] \| Real Estate [Member] \| Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	11,122	9,228
Pass [Member] \| Real Estate [Member] \| Mortgage Warehousing [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	105,133	98,156
Pass [Member] \| Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	306,718	274,959
Pass [Member] \| Consumer [Member] \| Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	36,458	29,781
Pass [Member] \| Consumer [Member] \| Direct Installment Purchased [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	236	294
Pass [Member] \| Consumer [Member] \| Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	138,540	130,851
Pass [Member] \| Consumer [Member] \| Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	131,484	114,033
Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	13,668	13,861
Percentage of total loans	1.02%	1.30%
Special Mention [Member] \| Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	13,668	13,861
Special Mention [Member] \| Commercial [Member] \| Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	4,753	2,231
Special Mention [Member] \| Commercial [Member] \| Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,668	5,047
Special Mention [Member] \| Commercial [Member] \| Residential Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	259
Special Mention [Member] \| Commercial [Member] \| Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	82	91
Special Mention [Member] \| Commercial [Member] \| Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,906	6,492
Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	29,593	34,709
Percentage of total loans	2.21%	3.25%
Substandard [Member] \| Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	24,556	23,903
Substandard [Member] \| Commercial [Member] \| Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	6,802	7,946
Substandard [Member] \| Commercial [Member] \| Non Owner Occupied Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	13,288	11,041
Substandard [Member] \| Commercial [Member] \| Development & Spec Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	1,113	1,340
Substandard [Member] \| Commercial [Member] \| Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	3,353	3,576
Substandard [Member] \| Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	2,471	6,146
Substandard [Member] \| Real Estate [Member] \| Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	2,471	5,866
Substandard [Member] \| Real Estate [Member] \| Residential Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Total		280
Substandard [Member] \| Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	2,566	4,660
Substandard [Member] \| Consumer [Member] \| Direct Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	262	202
Substandard [Member] \| Consumer [Member] \| Indirect Installment [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	598	533
Substandard [Member] \| Consumer [Member] \| Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Total	$ 1,706	$ 3,925
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Percentage of total loans	0.00%	0.00%