Securities - Amortized Cost and Fair Value of Available-for-sale Securities (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Debt securities available-for-sale:
Amortized Cost	$ 159,649,000	$ 153,566,000
Gross Unrealized Gains	205,000	165,000
Gross Unrealized Losses	(3,644,000)	(1,787,000)
Fair Value	156,209,802	151,944,567
U.S. Government-sponsored enterprises (GSEs) [Member]
Debt securities available-for-sale:
Amortized Cost	30,147,000	26,207,000
Gross Unrealized Gains	0	1,000
Gross Unrealized Losses	(844,000)	(432,000)
Fair Value	29,303,000	25,776,000
Municipal securities [Member]
Debt securities available-for-sale:
Amortized Cost	10,141,000	9,122,000
Gross Unrealized Gains	10,000	28,000
Gross Unrealized Losses	(265,000)	(147,000)
Fair Value	9,886,000	9,003,000
Other debt securities [Member]
Debt securities available-for-sale:
Amortized Cost	975,000	974,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(51,000)	(24,000)
Fair Value	924,000	950,000
Mortgage-backed securities (GSEs) [Member]
Debt securities available-for-sale:
Amortized Cost	118,386,000	117,263,000
Gross Unrealized Gains	195,000	136,000
Gross Unrealized Losses	(2,484,000)	(1,184,000)
Fair Value	$ 116,097,000	$ 116,215,000