Summary of Significant Accounting Policies - Premises and equipment (Details)	12 Months Ended
	Jun. 30, 2021
Office buildings and improvements | Minimum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	5 years
Office buildings and improvements | Maximum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	33 years
Furniture, fixtures and equipment | Minimum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	5 years
Furniture, fixtures and equipment | Maximum
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	10 years
Automobiles
Accounting Policies [Line items]
Property, Plant and Equipment, Useful Life	4 years