Name:	sp_MultiemployerPlansCollectiveBargainingArrangementEmployerContributionAsPercentageOfAggregateContributions
Namespace Prefix:	sp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Represents the amount of net expenses for contributions not reimbursed to the entity under a collective bargaining arrangement related to a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

No definition available.

Name:	sp_MultiemployerPlansCollectiveBargainingArrangementNetExpensesNotReimbursed
Namespace Prefix:	sp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Indicates the funded status of the multiemployer plan, expressed as a percentage.

No definition available.

Name:	sp_MultiemployerPlansFundedStatusPercentage
Namespace Prefix:	sp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Amount of contributions made to multiemployer plans by the employer. A multiemployer plan is a pension or postretirement benefit plan to which two or more unrelated employers contribute where assets contributed by one participating employer may be used to provide benefits to employees of other participating employers.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=49170332&loc=SL14450702-114947

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=49170332&loc=SL14450691-114947

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=49170332&loc=SL14450657-114947

Name:	us-gaap_MultiemployerPlanPeriodContributions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_MultiemployerPlansLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	sp_MultiemployerPlansCertifiedZoneStatusAxis=sp_RedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	sp_MultiemployerPlansCertifiedZoneStatusAxis=sp_YellowMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	sp_MultiemployerPlansCertifiedZoneStatusAxis=sp_GreenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_MultiemployerPlanNameAxis=sp_TeamstersLocalUnion727Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_MultiemployerPlanTypeAxis=us-gaap_MultiemployerPlansPensionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: