Rate and Maturity Information on Long-Term Federal Home Loan Bank Advances and Other Borrowings (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013		Dec. 31, 2012
Schedule Of Debt Instruments [Line Items]
Balance	$ 191,645		$ 161,315
Fixed Amortizing
Schedule Of Debt Instruments [Line Items]
Maturity Start Range	Apr. 08, 2015	[1]
Maturity End Range	Apr. 08, 2015	[1]
Weighted Average Rate	3.61%
Interest Rate Minimum	3.61%
Interest Rate Maximum	3.61%
Balance	2,485		4,285
Adjustable Amortizing
Schedule Of Debt Instruments [Line Items]
Maturity Start Range	Dec. 31, 2016	[1]
Maturity End Range	Dec. 31, 2016	[1]
Weighted Average Rate	3.25%
Interest Rate Minimum	3.25%
Interest Rate Maximum	3.25%
Balance	7,637		9,400
Bullet Maturity | Fixed Rate
Schedule Of Debt Instruments [Line Items]
Maturity Start Range	Mar. 23, 2015	[1]
Maturity End Range	Dec. 19, 2019	[1]
Weighted Average Rate	1.40%
Interest Rate Minimum	0.58%
Interest Rate Maximum	2.44%
Balance	135,000		90,000
Bullet Maturity | Variable Rate
Schedule Of Debt Instruments [Line Items]
Maturity Start Range	Jun. 25, 2015	[1]
Maturity End Range	Nov. 18, 2017	[1]
Weighted Average Rate	0.46%
Interest Rate Minimum	0.46%
Interest Rate Maximum	0.46%
Balance	25,000		15,000
Convertible-Fixed
Schedule Of Debt Instruments [Line Items]
Maturity Start Range	Jan. 03, 2018	[1],[2]
Maturity End Range	Aug. 20, 2018	[1],[2]
Weighted Average Rate	2.47%	[2]
Interest Rate Minimum	2.21%	[2]
Interest Rate Maximum	2.62%	[2]
Balance	$ 21,523	[2]	$ 42,630	[2]

[1] Maturity range refers to September 30, 2013 balances

[2] FHLB advances whereby the FHLB has the option, at predetermined times, to convert the fixed interest rate to an adjustable interest rate indexed to the London Interbank Offered Rate ("LIBOR"). The Corporation has the option to prepay these advances, without penalty, if the FHLB elects to convert the interest rate to an adjustable rate. As of September 30, 2013, substantially all the FHLB advances with this convertible feature are subject to conversion in fiscal 2013. These advances are included in the maturity ranges in which they mature, rather than the period in which they are subject to conversion.