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Securities - Amortized cost and fair value (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($) security	Dec. 31, 2020 USD ($) security
Securities available-for-sale:
Amortized Cost	$ 133,341	$ 120,215
Available-for-sale, Gross Unrealized Gains	1,947	3,504
Available-for-sale, Gross Unrealized Losses	(1,123)	(157)
Fair value	134,165	123,562
Securities held to maturity:
Held-to-maturity, Amortized Cost	6,476	6,510
Held-to-maturity, Gross Unrealized Gains	296	347
Fair Value	$ 6,772	$ 6,857
Number of securities in unrealized loss positions | security	47	14
Number of securities deemed other-than-temporarily impaired | security	0
Securities pledged as collateral fair value	$ 63,600	$ 55,900
U.S. asset backed securities
Securities available-for-sale:
Amortized Cost	26,828	25,303
Available-for-sale, Gross Unrealized Gains	458	364
Available-for-sale, Gross Unrealized Losses	(56)	(75)
Fair value	$ 27,230	$ 25,592
Securities held to maturity:
Number of securities in unrealized loss positions | security	7	8
U.S. government agency mortgage-backed securities
Securities available-for-sale:
Amortized Cost	$ 3,796	$ 3,854
Available-for-sale, Gross Unrealized Gains	126	192
Fair value	3,922	4,046
U.S. government agency collateralized mortgage obligations
Securities available-for-sale:
Amortized Cost	23,014	23,010
Available-for-sale, Gross Unrealized Gains	642	916
Available-for-sale, Gross Unrealized Losses	(137)	(17)
Fair value	$ 23,519	$ 23,909
Securities held to maturity:
Number of securities in unrealized loss positions | security	5	1
State and municipal securities
Securities available-for-sale:
Amortized Cost	$ 72,815	$ 63,848
Available-for-sale, Gross Unrealized Gains	704	2,025
Available-for-sale, Gross Unrealized Losses	(871)	(63)
Fair value	72,648	65,810
Securities held to maturity:
Held-to-maturity, Amortized Cost	6,476	6,510
Held-to-maturity, Gross Unrealized Gains	296	347
Fair Value	$ 6,772	$ 6,857
Number of securities in unrealized loss positions | security	30	3
Corporate bonds
Securities available-for-sale:
Amortized Cost	$ 4,950	$ 4,200
Available-for-sale, Gross Unrealized Gains	17	7
Available-for-sale, Gross Unrealized Losses	(37)	(2)
Fair value	$ 4,930	$ 4,205
Securities held to maturity:
Number of securities in unrealized loss positions | security	4	2
U.S. Treasuries
Securities available-for-sale:
Amortized Cost	$ 1,938
Available-for-sale, Gross Unrealized Losses	(22)
Fair value	$ 1,916
Securities held to maturity:
Number of securities in unrealized loss positions | security	1

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