Loans Receivable - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Loans Receivable [Line Items]
Interest income on impaired loans	$ 4,000,000	$ 5,100,000
Troubled debt restructurings, allowance	2,500,000	2,600,000
Loans classified as a Troubled Debt Restructurings	41,100,000	37,100,000
Non-accrual loans	22,800,000	19,400,000
Accrual loans status	18,300,000	17,700,000
Minimum period to reduce interest rate as a modification in term of loan	10 months
Maximum period to reduce interest rate as a modification in term of loan	7 years
Financing receivable modification extension period minimum	10 months
Financing receivable modification extension period maximum	5 years
Troubled debt restructurings, specific reserves	778,000	2,500,000
Troubled debt restructurings, charge-offs	279,000	928,000
Payment default classification period	90 days
Loans modified	$ 791,000	$ 7,200,000