Stock Based Compensation - Summary of Stock Options Outstanding and Exercisable (Details) - USD ($)		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares (in shares)		592,778	596,313	611,313	419,238
Options exercisable at end of year (in shares)	[1]	352,778	356,313	371,313
Granted in Prior Years
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise Price (in USD per share)		$ 8.66
Number of Shares (in shares)		352,778
Weighted Average Remaining Contractual Term (in years)		4 years 9 months
Aggregate Intrinsic Value		$ 7,203,727
Options exercisable at end of year (in shares)		352,778

[1] No options vested during the years ended December 31, 2017, 2016 or 2015.