Derivatives - Additional Information (Detail) (USD $)	0 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended
	Feb. 03, 2011	Dec. 31, 2013 Security	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 Federal home loan bank certificates and obligations FHLB [Member]	Mar. 31, 2012 Unrealized gains (losses) on derivatives [Member] Reclassification out of accumulated other comprehensive income [Member]	Dec. 31, 2013 Unrealized gains (losses) on derivatives [Member] Reclassification out of accumulated other comprehensive income [Member]	Aug. 31, 2011 Forward starting interest rate swap [Member] Contract	Aug. 31, 2010 Forward starting interest rate swap [Member] Contract	Feb. 04, 2011 Interest rate swap contracts [Member]	Jul. 31, 2013 Forward starting interest rate swap, One [Member]	Dec. 31, 2013 Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Number of interest rate swap contracts								4	5
Effective dates and maturities range, start date	Mar. 01, 2012
Effective, dates and maturities range, end date	Mar. 01, 2017
Cash realized on termination of forward starting interest rate swap positions										$ 3,000,000
Gains to be reclassified into earnings		7,935,000	7,560,000	6,684,000			3,000,000
Termination interest rate swap agreements					75,000,000
Net gains reclassified out of accumulated other comprehensive income		3,478,000	5,229,000	7,476,000		647,000	353,000
Interest expense on other borrowings												353,000
Previously forecasted amount of borrowings from Federal Home Loan Bank not obtained											75,000,000
Gain reclassified out of accumulated other comprehensive income to earnings											296,000
Loss recognized on termination of interest rate swap											503,000
Post collateral against its obligation		2,900,000
Number of mortgage backed securities pledged		4
Pledge on three mortgage backed securities		5,500,000
Fair market value of mortgage backed securities		$ 5,500,000