Basis of Presentation (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
1 Months Ended
Apr. 30, 2010
Sep. 30, 2012
Jun. 30, 2012
Apr. 05, 2010
Summary of Significant Accounting Policies [Line Items]        
Common stock issued in public offering, shares 2,464,274      
Common stock issued in public offering, per share issuance price $ 10.00      
Gross proceeds from common stock issued in public offering $ 24.6      
Shares of common stock received by existing stockholders for each share of Eagle Bancorp common stock that they owned immediately prior to completion of the exchange 3.800      
Common stock, shares authorized   8,000,000 8,000,000 8,000,000
Common stock, shares issued   4,083,127 4,083,127 4,083,127
Common stock, shares outstanding   3,878,971 3,878,971 4,083,127