Unpaid Claims and Claim Expenses - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2022	Sep. 30, 2021
Insurance Loss Reserves [Abstract]
Favorable development of total reserves for property and casualty claims occurring in prior years	$ 8.0	$ 7.2

Favorable Development Of Total Reserves For Property And Casualty Claims Occurring In Prior Years

No definition available.

Name:	hmn_FavorableDevelopmentOfTotalReservesForPropertyAndCasualtyClaimsOccurringInPriorYears
Namespace Prefix:	hmn_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant