Fair Value Measurements - Additional Information (Detail) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2013 Loans	Jun. 30, 2013 Loans	Dec. 31, 2012 Loans
Loans Receivable [Line Items]
Transfers out of Level 3	$ (344,000)	$ (344,000)
Number of loans, held for sale	0	0	0
Liabilities measured at estimated fair value on nonrecurring basis	0	0	0
Level 3 [Member]
Loans Receivable [Line Items]
Liabilities measured at fair value	$ 0	$ 0