Disclosure About Fair Values of Assets and Liabilities - collateral-dependent impaired loans at fair value on a nonrecurring basis (Details) - Non recurring - Collateral-dependent impaired loans - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Carrying value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of loan commitments	$ 259,678	$ 173,877
Level 3 | Fair value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of loan commitments	$ 259,678	$ 173,877