Summary of Significant Accounting Policies - Significant events (Details)			1 Months Ended	3 Months Ended	6 Months Ended	9 Months Ended
	May 08, 2020 USD ($) loan	Mar. 27, 2020	May 08, 2020 USD ($) loan	Mar. 31, 2020 USD ($) loan	Dec. 31, 2019 USD ($)	Mar. 31, 2020 USD ($) loan	Mar. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)	Jun. 30, 2018 USD ($)
Financing Receivable, Impaired [Line Items]
Number of loans modification request received | loan	88		88	88		88
Aggregate value of requested loans to be modified	$ 27,900,000		$ 27,900,000	$ 27,850,804		$ 27,850,804
Number of modified loans | loan	56
Aggregate value of loans modified	$ 12,900,000
Amount of performing modifications	$ 12,700,000		$ 12,700,000
Percentage of performing loans	98.50%
TDR's granted during the period | loan			1			0
TDR's outstanding	$ 194,000		$ 194,000	0		$ 0		$ 0
Provision for loan losses				85,000		85,000	$ 0
Allowance for loan losses				$ 1,303,434	$ 1,262,472	$ 1,303,434	$ 1,288,040	$ 1,293,965	$ 1,295,012	$ 1,324,159
Percentage of allowance for loan losses on total loans					0.50%	0.53%
Percentage of loan portfolio collateralized by real estate						99.20%
Percentage of loan portfolio to borrowers						1.60%
PPP
Financing Receivable, Impaired [Line Items]
Percentage of loan proceeds used for payroll costs		75.00%
Percentage of loan proceeds used for other qualifying expenses		25.00%
Number of loan originated | loan	13
Value of loan	$ 1,100,000		$ 1,100,000
Processing fee income	$ 35,000
PPP | Minimum
Financing Receivable, Impaired [Line Items]
Processing fee income (as a percent)		1.00%
Third party service fee payable (as a percent)		0.25%
PPP | Maximum
Financing Receivable, Impaired [Line Items]
Processing fee income (as a percent)		5.00%
Third party service fee payable (as a percent)		1.00%