Note 12 - Regulatory Capital and Oversight (Details Textual) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2018	Dec. 31, 2019
Banks Tangible Assets	$ 711.9
Adjusted Assets	710.2
Risk Weighted Assets	$ 614.9
Capital Conservation Buffer	1.875%
Scenario, Forecast [Member]
Capital Conservation Buffer		2.50%

Percentage of common equity tier 1 capital above its minimum risk-based capital requirements in order to avoid limitations on capital distributions, including dividend payments and certain discretionary bonus payments to executive officers.

No definition available.

Name:	hmnf_CapitalConservationBuffer
Namespace Prefix:	hmnf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration