Sale of Receivables (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Sale of Receivables [Abstract]
Sale of receivables to financial institutions	$ 206.4	$ 174.9	$ 547.0	$ 541.1
Charge related to sale of receivables	$ 4.3	$ 3.3	$ 11.2	$ 10.2

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