Loans, Allowance for Loan Losses, and Credit Quality Indicators - Schedule of Non-Covered Restructured Loans (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Rate Modification		$ 140
Term Modification	467	485
Interest Only Modification	351	928
Combination Modification	372	4,846
Commercial and other [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification
Term Modification	228
Interest Only Modification	230
Combination Modification	69	634
Consumer loans [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification
Term Modification
Interest Only Modification
Combination Modification
Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification		140
Term Modification	112	485
Interest Only Modification	121	928
Combination Modification	303	2,408
Real Estate [Member] | Multi-family residential [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification
Term Modification
Interest Only Modification
Combination Modification
Real Estate [Member] | Residential 1-4 family [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification		140
Term Modification		26
Interest Only Modification	121	928
Combination Modification		1,328
Real Estate [Member] | Owner-occupied commercial [Member]
Financing Receivable, Modifications [Line Items]
Term Modification	112	305
Combination Modification	303	555
Real Estate [Member] | Nonowner-occupied commercial [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification
Term Modification		154
Interest Only Modification
Combination Modification		525
Construction [Member]
Financing Receivable, Modifications [Line Items]
Term Modification	127
Combination Modification		1,804
Construction [Member] | Multi-family residential [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification
Term Modification
Construction [Member] | Residential 1-4 family [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification
Term Modification
Interest Only Modification
Combination Modification
Construction [Member] | Aged Analysis of Loans Receivable [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification
Term Modification
Interest Only Modification
Combination Modification
Construction [Member] | Commercial bare land and acquisition & development [Member]
Financing Receivable, Modifications [Line Items]
Term Modification
Combination Modification
Construction [Member] | Residential bare land and acquisition & development [Member]
Financing Receivable, Modifications [Line Items]
Rate Modification
Term Modification	127
Interest Only Modification
Combination Modification		$ 1,804