CONTINGENT LIABILITIES AND OTHER MATTERS (Details 4) - Consortium arrangements - Thermal Equipment and Services reportable segment - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 26, 2015	Dec. 31, 2014
Collaborative Arrangements
Entity's share of the aggregate contract value on open consortium arrangements	$ 84.0	$ 65.2
Percentage of entity's share of the aggregate contract value, recognized as revenue	79.00%	87.00%
Aggregate contract value on open consortium arrangements	$ 340.2	$ 291.1
Estimated fair value of potential obligation recorded as a liabilities	$ 0.5	$ 0.7

Represents the aggregate contract value on open consortium arrangements.

No definition available.

Name:	spxc_CollaborativeArrangementsAggregateContractValue
Namespace Prefix:	spxc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the entity's share of aggregate contract value on open consortium arrangements.

+ References

No definition available.

+ Details

Name:	spxc_CollaborativeArrangementsContractValue
Namespace Prefix:	spxc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the estimated fair value of potential obligation under the joint and several liability provisions associated with consortium arrangements, recorded as a liability.

+ References

No definition available.

+ Details

Name:	spxc_CollaborativeArrangementsEstimatedFairValueOfPotentialObligation
Namespace Prefix:	spxc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the percentage of entity's share of aggregate contract value which had been recognized as revenue.

+ References

No definition available.

+ Details

Name:	spxc_CollaborativeArrangementsPercentageOfRevenueRecognized
Namespace Prefix:	spxc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_TypeOfArrangementAxis=us-gaap_CollaborativeArrangementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=spxc_ThermalEquipmentAndServicesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: