Summary of Significant Accounting Policies - Mortgage Servicing Rights (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2022	Sep. 30, 2021
Mortgage Servicing Rights [Abstract]
Mortgage servicing fee income	$ 1.6	$ 0.6

Income from servicing real estate mortgages held by others net of any related impairment of capitalized service costs.

No definition available.

Name:	hnvr_MortgageLoanServicingIncome
Namespace Prefix:	hnvr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration