Nature of Operations and Summary of Significant Accounting Policies - Estimated Useful Lives of Premises and Equipment (Detail)	12 Months Ended
	Jun. 30, 2017
Minimum [Member] | Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	35 years
Minimum [Member] | Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Maximum [Member] | Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	40 years
Maximum [Member] | Furniture and Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful lives	5 years