Represents the percentage of ownership interest in joint venture sold.

No definition available.

Name:	spxc_EquityMethodInvestmentOwnershipPercentageSold
Namespace Prefix:	spxc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of days in the second and third quarter for which the entity reports its quarterly results of operations.

+ References

No definition available.

+ Details

Name:	spxc_NumberOfDaysInSecondAndThirdQuarter
Namespace Prefix:	spxc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the amount of net sales proceeds received on disposal of an equity method investment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 35

-Paragraph 35

-URI http://asc.fasb.org/extlink&oid=35687916&loc=d3e32847-111569

+ Details

Name:	us-gaap_EquityMethodInvestmentNetSalesProceeds
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of gain (loss) on sale or disposal of an equity method investment.

+ References

No definition available.

+ Details

Name:	us-gaap_EquityMethodInvestmentRealizedGainLossOnDisposal
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=spxc_EGSElectricalGroupLLCAndSubsidiariesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

BASIS OF PRESENTATION (Details 3) $ in Millions		3 Months Ended	9 Months Ended
BASIS OF PRESENTATION (Details 3) $ in Millions	Jan. 07, 2014 USD ($)	Mar. 29, 2014 USD ($)	Sep. 26, 2015 segment	Sep. 16, 2015 segment	Sep. 27, 2014 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments \| segment			3	2
Investment in joint venture under equity method investment
Length of second and third quarter			91 days
EGS Electrical Group, LLC and Subsidiaries ("EGS")
Investment in joint venture under equity method investment
Percentage of interest held in joint venture sold	44.50%
Cash proceeds from sale of interest in joint venture	$ 574.1
Gain on sale of interest in joint venture		$ 491.2			$ 491.2