Legal and Other Commitments and Contingencies - Contracts Acquired in the Central Merger (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Structural or other improvement and repair costs incurred	$ 0.1	$ 0.1	$ 0.1	$ 0.3
Estimated total structural and other improvement and repair costs related to lease contracts acquired in the Central Merger			$ 0.1

Represents the amount of structural or other improvement and repair costs incurred during the period pursuant to the contractual requirements of certain lease contracts acquired in the Central Merger.

No definition available.

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