Loans - Financing Receivables Modified as Troubled Debt Restructurings within Previous 12 Months for Payment Default (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013 Contract	Sep. 30, 2012 Contract	Sep. 30, 2013 Contract	Sep. 30, 2012 Contract
Schedule Of Financing Receivables [Line Items]
Troubled Debt Restructurings That Subsequently Defaulted, Number of Contracts	8	2	10	4
Troubled Debt Restructurings That Subsequently Defaulted, Record Investment	$ 592	$ 296	$ 1,773	$ 690
Residential: 1-4 family [Member]
Schedule Of Financing Receivables [Line Items]
Troubled Debt Restructurings That Subsequently Defaulted, Number of Contracts	8	2	8	4
Troubled Debt Restructurings That Subsequently Defaulted, Record Investment	592	296	592	690
Commercial [Member]
Schedule Of Financing Receivables [Line Items]
Troubled Debt Restructurings That Subsequently Defaulted, Number of Contracts			1	0
Troubled Debt Restructurings That Subsequently Defaulted, Record Investment			447	0
Commercial real estate: Other [Member]
Schedule Of Financing Receivables [Line Items]
Troubled Debt Restructurings That Subsequently Defaulted, Number of Contracts			1	0
Troubled Debt Restructurings That Subsequently Defaulted, Record Investment			$ 734	$ 0