Large Company Value Portfolio Investment Objectives and Goals - Large Company Value Portfolio	Dec. 31, 2025
Prospectus [Line Items]
Risk/Return [Heading]	Large Company Value Portfolio – Summary
Objective [Heading]	<span style="color:#000000;font-family:Arial;font-size:10.02pt;font-weight:bold;">INVESTMENT OBJECTIVE</span>
Objective, Primary [Text Block]	The investment objective of the Portfolio is to seek long-term capital growth.
Objective, Secondary [Text Block]	Income is a secondary objective.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 2
-Subsection a

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 2
-Subsection a

Name:	oef_ObjectivePrimaryTextBlock
Namespace Prefix:	oef_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 2
-Subsection a

Name:	oef_ObjectiveSecondaryTextBlock
Namespace Prefix:	oef_
Data Type:	dtr-types:textBlockItemType
Balance Type:	na
Period Type:	duration

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form N-1A
-Section 1
-Subsection a

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Section 2
-Name Form N-1A
-Subsection a

Name:	dei_LegalEntityAxis=nmsf_S000018227Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: