Basis of Presentation (Details)	Sep. 30, 2021
Basis of Presentation [Abstract]
Equity ownership in entities included in consolidated financial statements, minimum	50.00%

The threshold equity ownership percentage in the entities included in the consolidated financial statements.

No definition available.

Name:	smp_EquityOwnershipInEntitiesIncludedInConsolidatedFinancialStatementsThreshold
Namespace Prefix:	smp_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant