Loans and Allowance for Loan Losses - ALL Roll Forward (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	$ 5,860,000	$ 5,105,000	$ 5,105,000
Loans charged off	(158,000)		(276,000)
Recoveries of loans charged off	86,000		248,000
Provision (reallocation) charged to expense	688,796	12,450	783,000
Ending balance	6,477,000		5,860,000
Commercial Real Estate [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	2,465,000	2,369,000	2,369,000
Loans charged off	(38,000)		0
Recoveries of loans charged off	0		8,000
Provision (reallocation) charged to expense	498,000		88,000
Ending balance	2,925,000		2,465,000
Consumer Real Estate [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,596,000	1,382,000	1,382,000
Loans charged off	0		(111,000)
Recoveries of loans charged off	23,000		99,000
Provision (reallocation) charged to expense	(100,000)		226,000
Ending balance	1,519,000		1,596,000
Construction and Land Development [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	521,000	717,000	717,000
Loans charged off	0		0
Recoveries of loans charged off	2,000		13,000
Provision (reallocation) charged to expense	104,000		(209,000)
Ending balance	627,000		521,000
Commercial and Industrial [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	1,062,000	520,000	520,000
Loans charged off	(78,000)		(24,000)
Recoveries of loans charged off	40,000		67,000
Provision (reallocation) charged to expense	186,000		499,000
Ending balance	1,210,000		1,062,000
Consumer and Other [Member]
Allowance for Loan and Lease Losses [Roll Forward]
Beginning balance	216,000	$ 117,000	117,000
Loans charged off	(42,000)		(141,000)
Recoveries of loans charged off	21,000		61,000
Provision (reallocation) charged to expense	1,000		179,000
Ending balance	$ 196,000		$ 216,000