Loans - Loans by Class Modified as Troubled Debt Restructurings with Payment Default (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013 SecurityLoan	Dec. 31, 2012 SecurityLoan
Financing Receivable, Recorded Investment [Line Items]
Number of loans	22	11
Recorded Investment	$ 3,075	$ 928
Permanent Real Estate Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	11	9
Recorded Investment	1,815	851
Permanent Real Estate Loans [Member] | One-to Four-Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	8	9
Recorded Investment	861	851
Permanent Real Estate Loans [Member] | Multi-Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	1
Recorded Investment	467
Permanent Real Estate Loans [Member] | Nonresidential [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans
Recorded Investment
Permanent Real Estate Loans [Member] | Land [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	2
Recorded Investment	487
Construction Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	1
Recorded Investment	823
Construction Loans [Member] | One-to Four-Family Residential [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	1
Recorded Investment	823
Construction Loans [Member] | Multi-Family and Nonresidential [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans
Recorded Investment
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	10	2
Recorded Investment	437	77
Consumer Loans [Member] | Home Equity [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	8	2
Recorded Investment	250	77
Consumer Loans [Member] | Auto [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans
Recorded Investment
Consumer Loans [Member] | Marine [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans
Recorded Investment
Consumer Loans [Member] | Recreational Vehicles [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans	2
Recorded Investment	187
Consumer Loans [Member] | Others [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans
Recorded Investment
Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans
Recorded Investment
Commercial Loans [Member] | Secured [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans
Recorded Investment
Commercial Loans [Member] | Unsecured [Member]
Financing Receivable, Recorded Investment [Line Items]
Number of loans
Recorded Investment