Income Taxes - Reconciliation of income tax expense computed at satutory rate (Details 1) - USD ($)
 3 Months Ended 12 Months Ended
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2013
Sep. 30, 2013
Jun. 30, 2013
Mar. 31, 2013
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Income Tax Disclosure [Abstract]                              
Income before income tax expense (benefit) $ 552 $ (169) $ 786 $ 429 $ 521 $ 637 $ 498 $ 567 $ 814 $ 1,039 $ 788 $ 607 $ 1,597,537 $ 2,223,178 $ 3,248,032
Taxes computed at Federal income tax rate                         543,163 755,881 1,104,331
Increase (decrease) resulting from:                              
Tax-exempt income                         (441,890) (531,764) (630,710)
State income taxes, net of Federal income tax benefit                         141,966 101,933 160,027
Other                         1,682 (17,398) 207
Income tax expense                         $ 244,921 $ 308,652 $ 633,855