Loans - Summary of Loans Secured by Commercial Real Estate by Category (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in other loans held for sale	$ (7,088)	$ (14,178)
Gross Loans	733,940	773,558
Commercial Real Estate Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	451,384
Commercial real estate included in other loans held for sale	6,938
Gross Loans	458,322
Percentage of gross loans and commercial loans held for sale	61.80%
Percentage of regulatory capital	408.30%
Development Commercial Real Estate Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	59,160
Commercial real estate included in other loans held for sale	2,113
Gross Loans	61,273
Percentage of gross loans and commercial loans held for sale	8.30%
Percentage of regulatory capital	54.60%
Development Commercial Real Estate Loans [Member] | Land - unimproved (commercial or residential) [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	23,088
Gross Loans	23,088
Percentage of gross loans and commercial loans held for sale	3.10%
Percentage of regulatory capital	20.60%
Development Commercial Real Estate Loans [Member] | Land development - commercial [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	9,153
Gross Loans	9,153
Percentage of gross loans and commercial loans held for sale	1.20%
Percentage of regulatory capital	8.20%
Development Commercial Real Estate Loans [Member] | Land development - residential [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	11,607
Commercial real estate included in other loans held for sale	2,113
Gross Loans	13,720
Percentage of gross loans and commercial loans held for sale	1.90%
Percentage of regulatory capital	12.20%
Development Commercial Real Estate Loans [Member] | Retail [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	11,697
Gross Loans	11,697
Percentage of gross loans and commercial loans held for sale	1.60%
Percentage of regulatory capital	10.40%
Development Commercial Real Estate Loans [Member] | Office [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	230
Gross Loans	230
Percentage of regulatory capital	0.20%
Development Commercial Real Estate Loans [Member] | Industrial and Warehouse [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	823
Gross Loans	823
Percentage of gross loans and commercial loans held for sale	0.10%
Percentage of regulatory capital	0.70%
Development Commercial Real Estate Loans [Member] | Miscellaneous Commercial [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	2,562
Gross Loans	2,562
Percentage of gross loans and commercial loans held for sale	0.40%
Percentage of regulatory capital	2.30%
Existing and Other Commercial Real Estate Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	249,635
Commercial real estate included in other loans held for sale	4,825
Gross Loans	254,460
Percentage of gross loans and commercial loans held for sale	34.30%
Percentage of regulatory capital	226.70%
Existing and Other Commercial Real Estate Loans [Member] | Retail [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	19,953
Gross Loans	19,953
Percentage of gross loans and commercial loans held for sale	2.70%
Percentage of regulatory capital	17.80%
Existing and Other Commercial Real Estate Loans [Member] | Office [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	20,352
Gross Loans	20,352
Percentage of gross loans and commercial loans held for sale	2.70%
Percentage of regulatory capital	18.10%
Existing and Other Commercial Real Estate Loans [Member] | Industrial and Warehouse [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	9,167
Gross Loans	9,167
Percentage of gross loans and commercial loans held for sale	1.20%
Percentage of regulatory capital	8.20%
Existing and Other Commercial Real Estate Loans [Member] | Miscellaneous Commercial [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	103,928
Gross Loans	103,928
Percentage of gross loans and commercial loans held for sale	14.00%
Percentage of regulatory capital	92.60%
Existing and Other Commercial Real Estate Loans [Member] | Hotel / Motel [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	65,184
Commercial real estate included in other loans held for sale	4,825
Gross Loans	70,009
Percentage of gross loans and commercial loans held for sale	9.50%
Percentage of regulatory capital	62.40%
Existing and Other Commercial Real Estate Loans [Member] | Multifamily [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	12,547
Gross Loans	12,547
Percentage of gross loans and commercial loans held for sale	1.70%
Percentage of regulatory capital	11.20%
Existing and Other Commercial Real Estate Loans [Member] | Health care [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	18,222
Gross Loans	18,222
Percentage of gross loans and commercial loans held for sale	2.50%
Percentage of regulatory capital	16.20%
Existing and Other Commercial Real Estate Loans [Member] | Residential Construction - speculative [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	282
Gross Loans	282
Percentage of regulatory capital	0.20%
Commercial Real Estate Owner Occupied and Residential Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	142,589
Gross Loans	142,589
Percentage of gross loans and commercial loans held for sale	19.20%
Percentage of regulatory capital	127.00%
Commercial Real Estate Owner Occupied and Residential Loans [Member] | Commercial - owner occupied [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	131,491
Gross Loans	131,491
Percentage of gross loans and commercial loans held for sale	17.70%
Percentage of regulatory capital	117.10%
Commercial Real Estate Owner Occupied and Residential Loans [Member] | Commercial Construction - owner occupied [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	4,325
Gross Loans	4,325
Percentage of gross loans and commercial loans held for sale	0.60%
Percentage of regulatory capital	3.90%
Commercial Real Estate Owner Occupied and Residential Loans [Member] | Residential Construction - contract [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	6,773
Gross Loans	$ 6,773
Percentage of gross loans and commercial loans held for sale	0.90%
Percentage of regulatory capital	6.00%