Name:	ifrs-full_NoncurrentProvisionsAbstract
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The amount of non-current provisions other than provisions for employee benefits. [Refer: Non-current provisions]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2027-01-01
-Name IFRS
-Number 19
-IssueDate 2025-01-01
-Paragraph B9
-Subparagraph e
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=19&code=ifrs-tx-2025-en-r&anchor=para_B9_e&doctype=Appendix&subtype=B
-URIDate 2025-03-27

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2027-01-01
-Name IAS
-Number 1
-IssueDate 2025-01-01
-Paragraph 78
-Subparagraph d
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2025-en-b&anchor=para_78_d&doctype=Standard
-URIDate 2025-03-27

Name:	ifrs-full_OtherLongtermProvisions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The amount of current provisions other than provisions for employee benefits. [Refer: Provisions]

Name:	ifrs-full_OtherShorttermProvisions
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The increase (decrease) in other current provisions resulting from transfers and changes that the entity does not separately disclose in the same statement or note.

No definition available.

Name:	shmd_IncreaseDecreaseThroughTransfersAndOtherChangesOtherCurrentProvisions
Namespace Prefix:	shmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The increase (decrease) in other long-term provisions resulting from transfers and changes that the entity does not separately disclose in the same statement or note.

No definition available.

Name:	shmd_IncreaseDecreaseThroughTransfersAndOtherChangesOtherLongTermProvisions
Namespace Prefix:	shmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount recognised for new other long-term provisions.

No definition available.

Name:	shmd_NewProvisionsOtherLongTermProvisions
Namespace Prefix:	shmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount recognised for new other short-term provisions.

No definition available.

Name:	shmd_NewProvisionsOtherShortTermProvisions
Namespace Prefix:	shmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

The amount reversed for unused other short-term provisions.

No definition available.

Name:	shmd_ReversalOfUnusedAmountOtherShortTermProvisions
Namespace Prefix:	shmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of utilization of other long-term provisions.

No definition available.

Name:	shmd_UtilizationOtherLongTermProvisions
Namespace Prefix:	shmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The amount of utilization of other short-term provisions.

No definition available.

Name:	shmd_UtilizationOtherShortTermProvisions
Namespace Prefix:	shmd_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Name:	ifrs-full_ClassesOfProvisionsAxis=ifrs-full_WarrantyProvisionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_ClassesOfProvisionsAxis=shmd_JubileeProvisionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	ifrs-full_ClassesOfProvisionsAxis=ifrs-full_LegalProceedingsProvisionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: