Summary of Significant Accounting Policies - Narrative (Details) - USD ($)
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Accounting Policies [Abstract]    
Federal reserve bank minimum reserve required $ 434,000 $ 171,000
Number of days delinquent at which accrual of interest on loan is discontinued 90 days  
Federal home loan bank stock, par value (usd per share) $ 100