Pension Plans and Other Postretirement Benefits (Details Textual) (USD $) In Thousands, unless otherwise specified	9 Months Ended
Sep. 30, 2012 Age	Sep. 30, 2011
Pension Plans and Other Postretirement Benefits (Textual) [Abstract]
Effective Jan. 1, 2007, minimum age at which previous group health benefits were eliminated	65
Funding of health reimbursement accounts	$ 133	$ 153

Effective January 1, 2007, the minimum age at which the Company eliminated the previous group health insurance benefits for retirees, including elimination of pharmacy benefits for Medicare eligible retirees, and established a Health reimbursement Account ("HRA") for each eligible participant.

No definition available.

Name:	hmn_MinimumAgePreviousGroupHealthBenefitsEliminated
Namespace Prefix:	hmn_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration