Loss Contingency - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member]	Mar. 31, 2013 Significant Unobservable Inputs (Level 3) [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) [Member]
Loss Contingencies [Line Items]
Loan Held for Sale Exposed to Fraud						$ 5,200,000	$ 5,200,000
Loan Held for Sale Range of possible loss, Minimum					1,500,000	1,500,000	1,500,000
Loan Held For Sale Range of possible loss, Maximum					3,200,000	3,200,000	3,200,000
Loss contingency provided by management	0	0	2,000,000	0		2,000,000	2,000,000
Loan held for sale not exposed to fraud					1,000,000		1,000,000
Loans recovered in cash from alleged perpetrator					1,500,000		1,500,000
Loans transferred to Other assets					2,700,000		2,700,000
Loans contingency transferred to Other assets					$ 2,000,000		$ 2,000,000