Securities - Amortized cost and fair value (Details) $ in Thousands	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($) security
Securities available-for-sale:
Amortized Cost	$ 58,874	$ 50,942
Available-for-sale, Gross Unrealized Gains	366	119
Available-for-sale, Gross Unrealized Losses	(384)	(633)
Securities available-for-sale	58,856	50,428
Securities held to maturity:
Held-to-maturity, Amortized Cost	8,780	12,741
Held-to-maturity, Gross Unrealized Gains	223	17
Held-to-maturity, Gross Unrealized (Losses)		(103)
Fair Value	9,003	12,655
Securities pledged as collateral fair value	19,500	20,600
U.S. asset backed securities
Securities available-for-sale:
Amortized Cost	11,967
Available-for-sale, Gross Unrealized Losses	(101)
Securities available-for-sale	$ 11,866
Securities held to maturity:
Number of securities in unrealized loss positions \| security	9
U.S. government agency mortgage-backed securities
Securities available-for-sale:
Amortized Cost	$ 5,457	24,092
Available-for-sale, Gross Unrealized Gains	66	45
Available-for-sale, Gross Unrealized Losses	(26)	(271)
Securities available-for-sale	$ 5,497	$ 23,866
Securities held to maturity:
Number of securities in unrealized loss positions \| security	1	24
U.S. government agency collateralized mortgage obligations
Securities available-for-sale:
Amortized Cost	$ 35,096	$ 14,754
Available-for-sale, Gross Unrealized Gains	300	52
Available-for-sale, Gross Unrealized Losses	(173)	(142)
Securities available-for-sale	$ 35,223	$ 14,664
Securities held to maturity:
Number of securities in unrealized loss positions \| security	15	12
State and municipal securities
Securities available-for-sale:
Amortized Cost	$ 6,354	$ 11,096
Available-for-sale, Gross Unrealized Gains		22
Available-for-sale, Gross Unrealized Losses	(84)	(199)
Securities available-for-sale	6,270	10,919
Securities held to maturity:
Held-to-maturity, Amortized Cost	8,780	10,750
Held-to-maturity, Gross Unrealized Gains	223	17
Held-to-maturity, Gross Unrealized (Losses)		(90)
Fair Value	$ 9,003	$ 10,677
Number of securities in unrealized loss positions \| security	6	26
U.S. Treasuries
Securities held to maturity:
Held-to-maturity, Amortized Cost		$ 1,991
Held-to-maturity, Gross Unrealized (Losses)		(13)
Fair Value		$ 1,978
Number of securities in unrealized loss positions \| security		2
Investments in mutual funds
Securities available-for-sale:
Amortized Cost		$ 1,000
Available-for-sale, Gross Unrealized Losses		(21)
Securities available-for-sale	$ 1,000	$ 979
Securities held to maturity:
Number of securities in unrealized loss positions \| security		1

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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Amortized cost of 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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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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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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