Investment Securities Available For Sale - Additional Information (Detail) (USD $)	6 Months Ended				6 Months Ended			1 Months Ended	6 Months Ended				6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Mar. 31, 2012	Dec. 31, 2011	Jun. 30, 2012 Collateralized mortgage obligations issued by non-agency Securities	Jun. 30, 2011 Collateralized mortgage obligations issued by non-agency	Jun. 30, 2012 Fair Value Asset Transfers Out of Level Three, Into Level Two Collateralized mortgage obligations issued by non-agency	Nov. 30, 2007 Asset backed securities Entity	Jun. 30, 2012 Asset backed securities Investment		Jun. 30, 2011 Asset backed securities	Dec. 31, 2011 Asset backed securities	Jun. 30, 2012 Asset backed securities Future Period
Schedule of Available-for-sale Securities [Line Items]
Aggregate fair market value of securities pledges as collateral	$ 10,000,000			$ 12,000,000
Net gains on sales of securities available for sale net of taxes	776,000	33,000
Net gains on sales of securities available for sale, taxes	410,000	7,000
Proceeds from sale of securities available for sale	136,000,000	6,000,000
Portion of other-than-temporary impairment losses recognized in other comprehensive loss	2,021,000		2,001,000	2,053,000
Number of securities					1				1
Trust preferred securities, number of issuers								56
Trust preferred securities, number of U.S. depository institutions								45
Trust preferred securities, number of insurance companies								11
Trust preferred securities issued, value								363,000,000
Basis points over 3 months LIBOR								0.60%
Available for sale security purchased, face value								3,000,000
Available for sale security purchased, price as percentage of face amount								95.21%
Available for sale security purchased, price paid								2,856,420
Amortized Cost	100,992,000			149,987,000			669,000		2,247,000	[1]		2,324,000
Estimated Fair Value	99,111,000			147,909,000			657,000		237,000	[1]		380,000
Gross Unrealized Loss	2,208,000			2,804,000			12,000		2,010,000	[1]		1,944,000
Available-for-sale securities, default experienced									47,500,000
Percentage of default to total current collateral									13.20%
Security payment deferrals									49,500,000
Percentage of payment deferrals to total current collateral									13.70%
Estimated additional defaults									63,500,000
Assumption in estimating security defaults, future default rates									2.00%
Assumption in estimating security defaults, prepayment rates									0.00%				1.00%
Assumption in estimating security defaults, recovery rates									0.00%				15.00%
Impairment loss on securities									$ 0		$ 77,000
Credit support rate of total balance at issuance					2.50%	5.20%
One-to-four family, residential first mortgage loans, fixed interest rate term					5 years
Delinquencies over 60 days or over						3.80%

[1] Comprised of a security that represents an interest in a pool of trust preferred securities issued by U.S.-based banks and insurance companies