Loans - Summary of Loans Secured by Commercial Real Estate by Category (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Mortgage Loans on Real Estate [Line Items]
Total commercial real estate loans	$ 730,764	$ 738,282	$ 761,687
Commercial Real Estate Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	456,010
Commercial real estate included in other loans held for sale	776
Total commercial real estate loans	456,786
Percentage of gross loans and other loans held for sale	62.40%
Percentage of Bank's total regulatory capital	388.40%
Development Commercial Real Estate Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	56,887
Commercial real estate included in other loans held for sale	776
Total commercial real estate loans	57,663
Percentage of gross loans and other loans held for sale	7.90%
Percentage of Bank's total regulatory capital	49.00%
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	21,665
Commercial real estate included in other loans held for sale
Total commercial real estate loans	21,665
Percentage of gross loans and other loans held for sale	3.00%
Percentage of Bank's total regulatory capital	18.40%
Development Commercial Real Estate Loans [Member] | Land development - commercial [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	7,326
Commercial real estate included in other loans held for sale
Total commercial real estate loans	7,326
Percentage of gross loans and other loans held for sale	1.00%
Percentage of Bank's total regulatory capital	6.20%
Development Commercial Real Estate Loans [Member] | Land development - residential [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	9,128
Commercial real estate included in other loans held for sale	776
Total commercial real estate loans	9,904
Percentage of gross loans and other loans held for sale	1.30%
Percentage of Bank's total regulatory capital	8.40%
Development Commercial Real Estate Loans [Member] | Retail [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	3,471
Commercial real estate included in other loans held for sale
Total commercial real estate loans	3,471
Percentage of gross loans and other loans held for sale	0.50%
Percentage of Bank's total regulatory capital	2.90%
Development Commercial Real Estate Loans [Member] | Health care [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	5,251
Commercial real estate included in other loans held for sale
Total commercial real estate loans	5,251
Percentage of gross loans and other loans held for sale	0.70%
Percentage of Bank's total regulatory capital	4.50%
Development Commercial Real Estate Loans [Member] | Industrial and Warehouse [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	785
Commercial real estate included in other loans held for sale
Total commercial real estate loans	785
Percentage of gross loans and other loans held for sale	0.10%
Percentage of Bank's total 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	9,261
Commercial real estate included in other loans held for sale
Total commercial real estate loans	9,261
Percentage of gross loans and other loans held for sale	1.30%
Percentage of Bank's total regulatory capital	7.90%
Existing and Other Commercial Real Estate Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	250,917
Commercial real estate included in other loans held for sale
Total commercial real estate loans	250,917
Percentage of gross loans and other loans held for sale	34.30%
Percentage of Bank's total regulatory capital	213.40%
Existing and Other Commercial Real Estate Loans [Member] | Retail [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	26,862
Commercial real estate included in other loans held for sale
Total commercial real estate loans	26,862
Percentage of gross loans and other loans held for sale	3.70%
Percentage of Bank's total regulatory capital	22.80%
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	14,375
Commercial real estate included in other loans held for sale
Total commercial real estate loans	14,375
Percentage of gross loans and other loans held for sale	2.00%
Percentage of Bank's total regulatory capital	12.20%
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	9,324
Commercial real estate included in other loans held for sale
Total commercial real estate loans	9,324
Percentage of gross loans and other loans held for sale	1.30%
Percentage of Bank's total regulatory capital	7.90%
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	111,068
Commercial real estate included in other loans held for sale
Total commercial real estate loans	111,068
Percentage of gross loans and other loans held for sale	15.20%
Percentage of Bank's total regulatory capital	94.50%
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	66,189
Commercial real estate included in other loans held for sale
Total commercial real estate loans	66,189
Percentage of gross loans and other loans held for sale	9.00%
Percentage of Bank's total regulatory capital	56.30%
Existing and Other Commercial Real Estate Loans [Member] | Office [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	11,241
Commercial real estate included in other loans held for sale
Total commercial real estate loans	11,241
Percentage of gross loans and other loans held for sale	1.50%
Percentage of Bank's total regulatory capital	9.60%
Existing and Other Commercial Real Estate Loans [Member] | Multifamily [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	11,555
Commercial real estate included in other loans held for sale
Total commercial real estate loans	11,555
Percentage of gross loans and other loans held for sale	1.60%
Percentage of Bank's total regulatory capital	9.80%
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	303
Commercial real estate included in other loans held for sale
Total commercial real estate loans	303
Percentage of gross loans and other loans held for sale
Percentage of Bank's total regulatory capital	0.30%
Commercial Real Estate Owner Occupied and Residential Loans [Member]
Mortgage Loans on Real Estate [Line Items]
Commercial real estate included in gross loans	148,206
Commercial real estate included in other loans held for sale
Total commercial real estate loans	148,206
Percentage of gross loans and other loans held for sale	20.20%
Percentage of Bank's total regulatory capital	126.00%
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	137,388
Commercial real estate included in other loans held for sale
Total commercial real estate loans	137,388
Percentage of gross loans and other loans held for sale	18.80%
Percentage of Bank's total regulatory capital	116.80%
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	5,351
Commercial real estate included in other loans held for sale
Total commercial real estate loans	5,351
Percentage of gross loans and other loans held for sale	0.70%
Percentage of Bank's total regulatory capital	4.60%
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	5,467
Commercial real estate included in other loans held for sale
Total commercial real estate loans	$ 5,467
Percentage of gross loans and other loans held for sale	0.70%
Percentage of Bank's total regulatory capital	4.60%