Securities - Reconciliation from Amortized Cost to Estimated Fair Value of Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Available for sale at fair value:
Amortized cost	$ 48,596	$ 52,763
Gross unrealized gains	70	183
Gross unrealized losses	(1,792)	(659)
Securities available for sale	46,874	52,287
Held to maturity at cost:
Amortized cost	15,325	16,307
Gross unrealized gains	172	292
Gross unrealized losses	(481)	(253)
Estimated fair value	15,016	16,346
Equity securities:
Amortized cost	1,262	1,262
Gross unrealized gains	47	15
Gross unrealized losses	(109)	(71)
Estimated fair value	1,200	1,206
U.S. Government sponsored entities
Available for sale at fair value:
Amortized cost	5,760	5,765
Gross unrealized gains	0	0
Gross unrealized losses	(183)	(74)
Securities available for sale	5,577	5,691
Held to maturity at cost:
Amortized cost	2,789	3,026
Gross unrealized gains	0	0
Gross unrealized losses	(169)	(93)
Estimated fair value	2,620	2,933
State and political subdivisions
Available for sale at fair value:
Amortized cost	4,867	5,227
Gross unrealized gains	1	21
Gross unrealized losses	(209)	(56)
Securities available for sale	4,659	5,192
Held to maturity at cost:
Amortized cost	951	1,113
Gross unrealized gains	94	144
Gross unrealized losses	0	0
Estimated fair value	1,045	1,257
Residential mortgage-backed securities
Available for sale at fair value:
Amortized cost	28,315	32,111
Gross unrealized gains	69	153
Gross unrealized losses	(1,059)	(386)
Securities available for sale	27,325	31,878
Held to maturity at cost:
Amortized cost	3,469	3,958
Gross unrealized gains	16	59
Gross unrealized losses	(86)	(18)
Estimated fair value	3,399	3,999
Commercial mortgage-backed securities
Held to maturity at cost:
Amortized cost	3,599	3,685
Gross unrealized gains	0	0
Gross unrealized losses	(226)	(142)
Estimated fair value	3,373	3,543
Corporate and other securities
Available for sale at fair value:
Amortized cost	9,654	9,660
Gross unrealized gains	0	9
Gross unrealized losses	(341)	(143)
Securities available for sale	9,313	9,526
Held to maturity at cost:
Amortized cost	4,517	4,525
Gross unrealized gains	62	89
Gross unrealized losses	0	0
Estimated fair value	$ 4,579	$ 4,614

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