Fair Value of Financial Instruments - Significant unobservable inputs (Level 3) used in the valuation of assets and liabilities measured at fair value on a nonrecurring basis (Detail) - Fair Value, Measurements, Nonrecurring [Member] - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Fair Value	$ 305,297	$ 1,851,752
Impaired Loans [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Fair Value	$ 305,297	$ 544,502
Valuation Technique	Appraised value of collateral less estimated costs to sell
Measurement Input, Loss Severity [Member] | Impaired Loans [Member]
Fair Value Of Assets And Liabilities Measured On Non Recurring Basis [Line Items]
Estimated costs to sell	25.00%