Investment securities available for sale - Summary of investment securities available for sale having fair value and unrealized loss position (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Schedule of Available-for-sale Securities [Line Items]
Securities in a loss position for less than 12 Months, Fair Value	$ 4,344,000	$ 5,507,000
Securities in a loss position for less than 12 Months, Unrealized Losses	(136,000)	(33,000)
Securities in a loss position for more than 12 Months, Fair Value	1,619,000	6,308,000
Securities in a loss Position for more than 12 Months, Unrealized Losses	(85,000)	(82,000)
Total Fair Value	5,963,000	11,815,000
Total Unrealized Losses	(221,000)	(115,000)
U.S. Government Agencies Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in a loss position for less than 12 Months, Fair Value	0	2,001,000
Securities in a loss position for less than 12 Months, Unrealized Losses	0	(1,000)
Securities in a loss position for more than 12 Months, Fair Value	1,201,000	5,368,000
Securities in a loss Position for more than 12 Months, Unrealized Losses	(3,000)	(8,000)
Total Fair Value	1,201,000	7,369,000
Total Unrealized Losses	(3,000)	(9,000)
Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in a loss position for less than 12 Months, Fair Value		2,747,000
Securities in a loss position for less than 12 Months, Unrealized Losses		(26,000)
Securities in a loss position for more than 12 Months, Fair Value		0
Securities in a loss Position for more than 12 Months, Unrealized Losses		0
Total Fair Value		2,747,000
Total Unrealized Losses		(26,000)
Subordinated Debt [Member]
Schedule of Available-for-sale Securities [Line Items]
Securities in a loss position for less than 12 Months, Fair Value	4,344,000	759,000
Securities in a loss position for less than 12 Months, Unrealized Losses	(136,000)	(6,000)
Securities in a loss position for more than 12 Months, Fair Value	418,000	940,000
Securities in a loss Position for more than 12 Months, Unrealized Losses	(82,000)	(74,000)
Total Fair Value	4,762,000	1,699,000
Total Unrealized Losses	$ (218,000)	$ (80,000)

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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