Securities - Amortized cost and fair value (Details) $ in Thousands	Dec. 31, 2018 USD ($) security	Dec. 31, 2017 USD ($) security
Securities available-for-sale:
Available-for-sale, Amortized Cost	$ 50,942	$ 40,393
Available-for-sale, Gross Unrealized Gains	119	36
Available-for-sale, Gross Unrealized (Losses)	(633)	(423)
Available-for-sale, Fair Value	50,428	40,006
Securities held to maturity:
Held-to-maturity, Amortized Cost	12,741	12,861
Held-to-maturity, Gross Unrealized Gains	17	86
Held-to-maturity, Gross Unrealized (Losses)	(103)	(78)
Fair Value	12,655	12,869
Securities pledged as collateral fair value	20,600	22,600
U.S. government agency mortgage-backed securities
Securities available-for-sale:
Available-for-sale, Amortized Cost	24,092	21,439
Available-for-sale, Gross Unrealized Gains	45	19
Available-for-sale, Gross Unrealized (Losses)	(271)	(190)
Available-for-sale, Fair Value	$ 23,866	21,268
Securities held to maturity:
Number of securities in unrealized loss positions \| security	24
U.S. government agency collateralized mortgage obligations
Securities available-for-sale:
Available-for-sale, Amortized Cost	$ 14,754	7,875
Available-for-sale, Gross Unrealized Gains	52	2
Available-for-sale, Gross Unrealized (Losses)	(142)	(99)
Available-for-sale, Fair Value	$ 14,664	$ 7,778
Securities held to maturity:
Number of securities in unrealized loss positions \| security	12	2
State and municipal securities
Securities available-for-sale:
Available-for-sale, Amortized Cost	$ 11,096	$ 10,079
Available-for-sale, Gross Unrealized Gains	22	14
Available-for-sale, Gross Unrealized (Losses)	(199)	(134)
Available-for-sale, Fair Value	10,919	9,959
Securities held to maturity:
Held-to-maturity, Amortized Cost	10,750	10,883
Held-to-maturity, Gross Unrealized Gains	17	86
Held-to-maturity, Gross Unrealized (Losses)	(90)	(70)
Fair Value	$ 10,677	$ 10,899
Number of securities in unrealized loss positions \| security	26	14
Investments in mutual funds and other equity securities
Securities available-for-sale:
Available-for-sale, Amortized Cost	$ 1,000	$ 1,000
Available-for-sale, Gross Unrealized Gains		1
Available-for-sale, Gross Unrealized (Losses)	(21)
Available-for-sale, Fair Value	$ 979	1,001
Securities held to maturity:
Number of securities in unrealized loss positions \| security	1
U.S. Treasuries
Securities held to maturity:
Held-to-maturity, Amortized Cost	$ 1,991	1,978
Held-to-maturity, Gross Unrealized (Losses)	(13)	(8)
Fair Value	$ 1,978	$ 1,970
Number of securities in unrealized loss positions \| security	2	13

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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Number of investment positions in available-for-sale investments in a continuous unrealized loss position for which an other-than-temporary impairment (OTTI) has not been recognized in the income statement.

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Amount of investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrecognized gain on investment in debt security measured at amortized cost (held-to-maturity).

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Amount of accumulated unrealized loss on investment in debt security measured at amortized cost (held-to-maturity).

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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