Loans and Allowance for Loan Losses - Credit risk profile (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 181,551,161	$ 173,852,016
Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	179,087,898	170,261,423
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,112,716	1,894,341
Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	1,350,547	1,696,252
Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
One- to Four- Family Mortgage Loans Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	91,919,064	93,659,520
One- to Four- Family Mortgage Loans Owner Occupied [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	91,281,765	92,776,661
One- to Four- Family Mortgage Loans Owner Occupied [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
One- to Four- Family Mortgage Loans Owner Occupied [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	637,299	882,859
One- to Four- Family Mortgage Loans Owner Occupied [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
One- to Four- Family Mortgage Loans Owner Occupied [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
One To Four Family Investment Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	12,846,342	14,242,563
One To Four Family Investment Mortgage Loans [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	12,115,427	13,010,425
One To Four Family Investment Mortgage Loans [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	548,876	1,101,684
One To Four Family Investment Mortgage Loans [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	182,039	130,454
One To Four Family Investment Mortgage Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
One To Four Family Investment Mortgage Loans [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Multi-Family Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	36,628,238	27,140,014
Multi-Family Mortgage Loans [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	36,256,469	26,509,203
Multi-Family Mortgage Loans [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	138,723
Multi-Family Mortgage Loans [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	371,769	492,088
Multi-Family Mortgage Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Multi-Family Mortgage Loans [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Nonresidential Mortgage Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	23,377,598	18,930,426
Nonresidential Mortgage Loans [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	22,813,758	18,234,663
Nonresidential Mortgage Loans [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	563,840	627,934
Nonresidential Mortgage Loans [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	67,829
Nonresidential Mortgage Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Nonresidential Mortgage Loans [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Construction & Land Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	5,329,188	7,293,737
Construction & Land Loans [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	5,329,188	7,293,737
Construction & Land Loans [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Construction & Land Loans [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Construction & Land Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Construction & Land Loans [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Real Estate Secured Lines of Credit [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	10,029,917	11,373,975
Real Estate Secured Lines of Credit [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	9,870,477	11,225,481
Real Estate Secured Lines of Credit [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	26,000
Real Estate Secured Lines of Credit [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	159,440	122,494
Real Estate Secured Lines of Credit [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Real Estate Secured Lines of Credit [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Commercial Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	557,268	415,730
Commercial Loans [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	557,268	415,730
Commercial Loans [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Commercial Loans [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Commercial Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Commercial Loans [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Other Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	863,546	796,051
Other Consumer Loans [Member] | Pass
Financing Receivable, Recorded Investment [Line Items]
Total loans	863,546	795,523
Other Consumer Loans [Member] | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Other Consumer Loans [Member] | Substandard
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	528
Other Consumer Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	0	0
Other Consumer Loans [Member] | Loss [Member]
Financing Receivable, Recorded Investment [Line Items]
Total loans	$ 0	$ 0