Securities - Amortized cost and fair value (Details) $ in Thousands	Sep. 30, 2019 USD ($) security	Dec. 31, 2018 USD ($) security
Securities available-for-sale:
Available-for-sale, Amortized Cost	$ 52,496	$ 50,942
Available-for-sale, Gross Unrealized Gains	476	119
Available-for-sale, Gross Unrealized Losses	(215)	(633)
Available-for-sale, Fair Value	52,757	50,428
Securities held to maturity:
Held-to-maturity, Amortized Cost	8,814	12,741
Held-to-maturity, Gross Unrealized Gains	214	17
Held-to-maturity, Gross Unrealized (Losses)		(103)
Fair Value	9,028	12,655
U.S. asset backed securities
Securities available-for-sale:
Available-for-sale, Amortized Cost	8,919
Available-for-sale, Gross Unrealized Gains	2
Available-for-sale, Gross Unrealized Losses	(39)
Available-for-sale, Fair Value	$ 8,882
Securities held to maturity:
Number of securities in unrealized loss positions \| security	5
U.S. government agency mortgage-backed securities
Securities available-for-sale:
Available-for-sale, Amortized Cost	$ 12,843	24,092
Available-for-sale, Gross Unrealized Gains	103	45
Available-for-sale, Gross Unrealized Losses	(46)	(271)
Available-for-sale, Fair Value	$ 12,900	$ 23,866
Securities held to maturity:
Number of securities in unrealized loss positions \| security	7	24
U.S. government agency collateralized mortgage obligations
Securities available-for-sale:
Available-for-sale, Amortized Cost	$ 29,734	$ 14,754
Available-for-sale, Gross Unrealized Gains	357	52
Available-for-sale, Gross Unrealized Losses	(130)	(142)
Available-for-sale, Fair Value	$ 29,961	$ 14,664
Securities held to maturity:
Number of securities in unrealized loss positions \| security	13	12
State and municipal securities
Securities available-for-sale:
Available-for-sale, Amortized Cost		$ 11,096
Available-for-sale, Gross Unrealized Gains		22
Available-for-sale, Gross Unrealized Losses		(199)
Available-for-sale, Fair Value		10,919
Securities held to maturity:
Held-to-maturity, Amortized Cost	$ 8,814	10,750
Held-to-maturity, Gross Unrealized Gains	214	17
Held-to-maturity, Gross Unrealized (Losses)		(90)
Fair Value	9,028	$ 10,677
Number of securities in unrealized loss positions \| security		26
Investments in mutual funds
Securities available-for-sale:
Available-for-sale, Amortized Cost	1,000	$ 1,000
Available-for-sale, Gross Unrealized Gains	14
Available-for-sale, Gross Unrealized Losses		(21)
Available-for-sale, Fair Value	$ 1,014	$ 979
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
Held-to-maturity, Gross Unrealized (Losses)		(13)
Fair Value		$ 1,978
Number of securities in unrealized loss positions \| security		2

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

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