Office Properties and Equipment, net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Office Properties and Equipment
Office properties and equipment, gross	$ 5,561	$ 5,491
Less accumulated depreciation	(3,155)	(3,012)
Office properties and equipment, net	2,406	2,479
Depreciation expense	256	251
Rent expense	587	566
Land
Office Properties and Equipment
Office properties and equipment, gross	572	572
Buildings and related components
Office Properties and Equipment
Office properties and equipment, gross	3,203	3,114
Furniture, fixtures and equipment
Office Properties and Equipment
Office properties and equipment, gross	$ 1,786	$ 1,805