Goodwill - Additional Information (Detail)	6 Months Ended
Jul. 01, 2012 Segment
Goodwill [Line Items]
Number of reporting units used for goodwill impairment testing	2

Number of segments used for goodwill impairment testing purpose. A reporting unit is an operating segment or one level below an operating segment (a component).

No definition available.

Name:	sr_NumberOfReportingUnits
Namespace Prefix:	sr_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration