Goodwill and Intangibles - Intangible assets - (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Intangible assets
Amortization of intangible assets	$ 218,000	$ 218,000	$ 82,000
Summary
Gross Carrying Amount	5,581,000	4,011,000	1,594,000
Accumulated Amortization	(1,782,000)	(469,000)	(82,000)
Total	$ 3,799,000	3,542,000	1,512,000
Licenses
Intangible assets
Amortization period	84 months
Summary
Gross Carrying Amount	$ 1,370,000	1,370,000	1,370,000
Accumulated Amortization	(465,000)	(269,000)	(74,000)
Total	$ 905,000	1,101,000	1,296,000
Trade names
Intangible assets
Amortization period	120 months
Summary
Gross Carrying Amount	$ 224,000	224,000	224,000
Accumulated Amortization	(53,000)	(31,000)	(8,000)
Total	$ 171,000	193,000	$ 216,000
Core Deposits
Intangible assets
Amortization period	10 years
Summary
Gross Carrying Amount	$ 2,417,000	2,417,000
Accumulated Amortization	(591,000)	(169,000)
Total	1,826,000	$ 2,248,000
Customer Lists
Intangible assets
Amortization period		21 months
Summary
Gross Carrying Amount	1,570,000
Accumulated Amortization	(673,000)
Total	$ 897,000
NattyMac, LLC | Customer Lists
Intangible assets
Amortization period	21 months	21 months
Amortization of intangible assets	$ 673,000
Summary
Total	$ 1,600,000
FMNBP | Core Deposits
Intangible assets
Amortization period	10 years
Amortization of intangible assets	$ 339,000	$ 85,000
FMBI | Core Deposits
Intangible assets
Amortization period	10 years
Amortization of intangible assets	$ 82,000	$ 84,000