Sale of Receivables (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Sale of Receivables [Abstract]
Sale of receivables to financial institutions	$ 690.3smp_SaleOfReceivables	$ 672.8smp_SaleOfReceivables
Charge related to sale of receivables	$ 13.1smp_SaleOfReceivablesRelatedCharges	$ 13.9smp_SaleOfReceivablesRelatedCharges	$ 13.7smp_SaleOfReceivablesRelatedCharges

The amount of charges incurred relating to the sale of receivables during the reporting period.

No definition available.

Name:	smp_SaleOfReceivablesRelatedCharges
Namespace Prefix:	smp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration