Summary of Significant Accounting Policies - Allowance for Loan Losses (Details)	12 Months Ended
Sep. 30, 2023
Allowance For Loan Losses [Abstract]
Historical loss lookback period	3 years

The lookback period is used to historical loss experience is applied to each loan group, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	hnvr_HistoricalLossLookbackPeriod
Namespace Prefix:	hnvr_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration