Loans, Allowance for Loan Losses, and Credit Quality Indicators - Schedule of Troubled Debt Restructurings that Subsequently Defaulted (Detail) (USD $)	Dec. 31, 2012 Contract	Dec. 31, 2011 Contract
Financing Receivable, Modifications [Line Items]
Number of Contracts	4	6
Recorded Investment	$ 945	$ 2,768
Commercial and other [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	1
Recorded Investment	194	634
Consumer loans [Member]
Financing Receivable, Modifications [Line Items]
Recorded Investment
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	3	3
Recorded Investment	751	1,692
Real Estate [Member] | Multi-family residential [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts
Recorded Investment
Real Estate [Member] | Residential 1-4 family [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	2	1
Recorded Investment	340	738
Real Estate [Member] | Owner-occupied commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts	1	1
Recorded Investment	411	429
Real Estate [Member] | Nonowner-occupied commercial [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts		1
Recorded Investment		525
Construction [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts		2
Recorded Investment		442
Construction [Member] | Multi-family residential [Member]
Financing Receivable, Modifications [Line Items]
Recorded Investment
Construction [Member] | Residential 1-4 family [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts
Construction [Member] | Aged Analysis of Loans Receivable [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts
Construction [Member] | Commercial bare land and acquisition & development [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts
Recorded Investment
Construction [Member] | Residential bare land and acquisition & development [Member]
Financing Receivable, Modifications [Line Items]
Number of Contracts		2
Recorded Investment		$ 442