Expense Example - Service Shares - Federated Hermes Treasury Obligations Fund - SS	Sep. 30, 2021 USD ($)
Expense Example:
1 Year	$ 54
3 Years	170
5 Years	296
10 Years	$ 665

No definition available.

Name:	rr_ExpenseExampleAbstract
Namespace Prefix:	rr_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then you redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return per year and that the Fund's operating expenses remained the same. Although your actual costs may be higher or lower.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 3
-Subsection instructions
-Paragraph 4

+ Details

Name:	rr_ExpenseExampleYear01
Namespace Prefix:	rr_
Data Type:	rr:NonNegativeMonetaryType
Balance Type:	na
Period Type:	duration

- Definition

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 3
-Subsection example
-Paragraph 1
-Subparagraph 2

+ Details

Name:	rr_ExpenseExampleYear03
Namespace Prefix:	rr_
Data Type:	rr:NonNegativeMonetaryType
Balance Type:	na
Period Type:	duration

- Definition

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 3
-Subsection example
-Paragraph 1
-Subparagraph 2

+ Details

Name:	rr_ExpenseExampleYear05
Namespace Prefix:	rr_
Data Type:	rr:NonNegativeMonetaryType
Balance Type:	na
Period Type:	duration

- Definition

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 3
-Subsection example
-Paragraph 1
-Subparagraph 2

+ Details

Name:	rr_ExpenseExampleYear10
Namespace Prefix:	rr_
Data Type:	rr:NonNegativeMonetaryType
Balance Type:	na
Period Type:	duration

- Details

Name:	dei_DocumentInformationDocumentAxis=fhmmot_ServiceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=fhmmot_S000009578Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	rr_ProspectusShareClassAxis=fhmmot_C000026168Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: