Summary of Loans by Portfolio Type and Internal Credit Quality Ratings (Detail) (USD $)	6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Gross loans	$ 708,398,000	$ 658,279,000
Increase (Decrease) in loan portfolios	50,119,000
Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	173,637,000	179,305,000
Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	31,959,000	24,358,000
Commercial real estate | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Gross loans	158,039,000	170,960,000
Commercial real estate | All other
Financing Receivable, Recorded Investment [Line Items]
Gross loans	155,118,000	121,813,000
Residential mortgage loans | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Gross loans	74,930,000	65,545,000
Residential mortgage loans | Residential mortgage loans - single family
Financing Receivable, Recorded Investment [Line Items]
Gross loans	87,227,000	68,613,000
Construction loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans		2,047,000
Land development loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	27,488,000	25,638,000
Pass
Financing Receivable, Recorded Investment [Line Items]
Gross loans	607,636,000	576,321,000
Increase (Decrease) in loan portfolios	31,315,000
Pass | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	135,717,000	149,522,000
Increase (Decrease) in loan portfolios	(13,805,000)
Pass | Consumer loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	31,959,000	24,358,000
Increase (Decrease) in loan portfolios	7,601,000
Pass | Commercial real estate | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Gross loans	137,474,000	148,380,000
Increase (Decrease) in loan portfolios	(10,906,000)
Pass | Commercial real estate | All other
Financing Receivable, Recorded Investment [Line Items]
Gross loans	134,013,000	109,482,000
Increase (Decrease) in loan portfolios	24,531,000
Pass | Residential mortgage loans | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Gross loans	71,020,000	61,190,000
Increase (Decrease) in loan portfolios	9,830,000
Pass | Residential mortgage loans | Residential mortgage loans - single family
Financing Receivable, Recorded Investment [Line Items]
Gross loans	85,418,000	66,631,000
Increase (Decrease) in loan portfolios	18,787,000
Pass | Land development loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	12,035,000	16,758,000
Increase (Decrease) in loan portfolios	(4,723,000)
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Gross loans	26,649,000	26,609,000
Increase (Decrease) in loan portfolios	40,000
Special Mention | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	10,250,000	4,570,000
Increase (Decrease) in loan portfolios	5,680,000
Special Mention | Commercial real estate | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Gross loans		6,826,000
Increase (Decrease) in loan portfolios	(6,826,000)
Special Mention | Commercial real estate | All other
Financing Receivable, Recorded Investment [Line Items]
Gross loans	3,888,000	2,553,000
Increase (Decrease) in loan portfolios	1,335,000
Special Mention | Residential mortgage loans | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Gross loans	3,910,000	3,316,000
Increase (Decrease) in loan portfolios	594,000
Special Mention | Residential mortgage loans | Residential mortgage loans - single family
Financing Receivable, Recorded Investment [Line Items]
Gross loans	347,000	1,014,000
Increase (Decrease) in loan portfolios	(667,000)
Special Mention | Land development loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	8,254,000	8,330,000
Increase (Decrease) in loan portfolios	(76,000)
Substandard
Financing Receivable, Recorded Investment [Line Items]
Gross loans	74,113,000	54,687,000
Increase (Decrease) in loan portfolios	19,426,000
Substandard | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	27,670,000	24,551,000
Increase (Decrease) in loan portfolios	3,119,000
Substandard | Commercial real estate | Owner occupied
Financing Receivable, Recorded Investment [Line Items]
Gross loans	20,565,000	15,754,000
Increase (Decrease) in loan portfolios	4,811,000
Substandard | Commercial real estate | All other
Financing Receivable, Recorded Investment [Line Items]
Gross loans	17,218,000	9,778,000
Increase (Decrease) in loan portfolios	7,440,000
Substandard | Residential mortgage loans | Multi-family
Financing Receivable, Recorded Investment [Line Items]
Gross loans		1,039,000
Increase (Decrease) in loan portfolios	(1,039,000)
Substandard | Residential mortgage loans | Residential mortgage loans - single family
Financing Receivable, Recorded Investment [Line Items]
Gross loans	1,461,000	968,000
Increase (Decrease) in loan portfolios	493,000
Substandard | Construction loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans		2,047,000
Increase (Decrease) in loan portfolios	(2,047,000)
Substandard | Land development loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans	7,199,000	550,000
Increase (Decrease) in loan portfolios	6,649,000
Doubtful
Financing Receivable, Recorded Investment [Line Items]
Gross loans	0	662,000
Increase (Decrease) in loan portfolios	(662,000)
Doubtful | Commercial loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans		662,000
Increase (Decrease) in loan portfolios	(662,000)
Doubtful | Land development loans
Financing Receivable, Recorded Investment [Line Items]
Gross loans