Debt Instrument, Face Amount, Returned Bank Bonds

No definition available.

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

- Definition

Number Of Large Power Projects

+ References

No definition available.

+ Details

Name:	spxc_NumberOfLargePowerProjects
Namespace Prefix:	spxc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount or range of possible amounts of gain that could be realized upon the resolution of a contingency.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

+ Details

Name:	us-gaap_GainContingencyUnrecordedAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount recovered from insurance. These recoveries reduce costs and losses that are reported as a separate line item under operating expenses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

+ Details

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

- Definition

Carrying amount as of the balance sheet date of reserves for the costs of settling insured claims and costs incurred in the claims settlement process attributable to asbestos and environmental claims, before estimated recoveries from reinsurers.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=116884095&loc=d3e14764-158437

+ Details

Name:	us-gaap_LiabilityForAsbestosAndEnvironmentalClaimsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount, after effects of reinsurance, of payments to settle insured claims and pay costs incurred in the claims settlement process attributable to asbestos and environmental claims.

+ References

+ Details

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

- Definition

Amount awarded to other party in judgment or settlement of litigation.

+ References

No definition available.

+ Details

Name:	us-gaap_LitigationSettlementAmountAwardedToOtherParty
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of loss contingency liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14326-108349

+ Details

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of loss contingency liability expected to be resolved after one year or beyond the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_LossContingencyAccrualCarryingValueNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14435-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118942415&loc=d3e14557-108349

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12021-110248

+ Details

Name:	us-gaap_LossContingencyEstimateOfPossibleLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of defendants named in a legal action.

+ References

No definition available.

+ Details

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

- Definition

Amount of receivable related to a loss contingency accrual that is expected to be collected after one year or beyond the normal operating cycle, if longer. For example, an insurance recovery receivable.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118943654&loc=d3e12053-110248

+ Details

Name:	us-gaap_LossContingencyReceivableNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

+ Details

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

- Definition

Amount of cost incurred on construction contract for unapproved change order, claim, or similar item subject to uncertainty.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 910
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6471471&loc=d3e48698-109348

+ Details

Name:	us-gaap_UnapprovedChangeOrdersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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

- Details

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

- Details

Name:	srt_StatementGeographicalAxis=country_ZA
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ChangeInAccountingEstimateByTypeAxis=us-gaap_ContractsAccountedForUnderPercentageOfCompletionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=spxc_OtherLongTermLiabilitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=spxc_DemandBondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=spxc_DemandBondsStringentPaymentRequirementsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LossContingenciesByNatureOfContingencyAxis=us-gaap_AsbestosIssueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BalanceSheetLocationAxis=us-gaap_OtherAssetsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=spxc_AlstomGEMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_BondsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_LitigationCaseAxis=spxc_DBTTechnologiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

CONTINGENT LIABILITIES AND OTHER MATTERS (Details) R in Millions, $ in Millions			3 Months Ended			6 Months Ended
	Oct. 30, 2018 USD ($)	Oct. 30, 2018 ZAR (R)	Jun. 29, 2019 USD ($)	Mar. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 29, 2019 USD ($) corporate_entity project	Jun. 30, 2018 USD ($)	Jul. 31, 2019 USD ($)	Jul. 31, 2019 ZAR (R)	Jun. 29, 2019 ZAR (R)	Jun. 28, 2019 USD ($)	Apr. 30, 2019 USD ($)	Apr. 30, 2019 ZAR (R)	Mar. 30, 2019 ZAR (R)	Feb. 26, 2019 USD ($)	Feb. 26, 2019 ZAR (R)	Dec. 31, 2018 USD ($)
Contingent Liabilities and Other Matters
Carrying values of accruals			$ 600.9			$ 600.9											$ 631.7
Liability for asbestos product liability matters			556.7			556.7											587.5
Insurance recoveries						26.6
Payments for asbestos-related matters, net of insurance recoveries						$ 6.3	$ 19.4
Number of large power projects \| project						2
Revenues			372.4		$ 379.2	$ 716.0	731.1
All Other
Contingent Liabilities and Other Matters
Revenues			0.8		$ 29.5	(7.1)	60.3
Large Power Projects \| SOUTH AFRICA
Contingent Liabilities and Other Matters
Gain contingency			72.6			72.6				R 1,033.3
Revenues related to claims and unapproved change orders			10.8			10.8
Estimate of possible legal claim deemed unlikely				$ 19.5								$ 18.6	R 264.4	R 277.5	$ 66.6	R 948.0
Large Power Projects \| SOUTH AFRICA \| Contracts Accounted for under Percentage of Completion \| All Other \| Operating Segments
Contingent Liabilities and Other Matters
Revenues			(6.0)	$ (17.5)		10.8
Other Long Term Liabilities
Contingent Liabilities and Other Matters
Accruals included in other long-term liabilities			573.2			573.2											600.3
Demand Bonds [Member]
Contingent Liabilities and Other Matters
Bonds issued			68.9			68.9
Demand Bonds, Stringent Payment Requirements
Contingent Liabilities and Other Matters
Bonds issued			23.0			23.0
Asbestos Issue
Contingent Liabilities and Other Matters
Insurance recoveries							$ 7.8
Asbestos Issue \| Other Assets
Contingent Liabilities and Other Matters
Insurance recovery assets			516.4			$ 516.4											$ 541.9
Alstom/GE \| Large Power Projects \| SOUTH AFRICA \| Contracts Accounted for under Percentage of Completion \| All Other \| Operating Segments
Contingent Liabilities and Other Matters
Revenues			$ (5.8)
Alstom/GE \| Bonds \| Large Power Projects \| SOUTH AFRICA
Contingent Liabilities and Other Matters
Bank bonds returned											$ 11.5
DBT Technologies
Contingent Liabilities and Other Matters
Loss contingency, estimate of possible loss	$ 18.0	R 256.0
Minimum \| Asbestos Issue
Contingent Liabilities and Other Matters
Number of corporate entities named as defendants \| corporate_entity						50
Subsequent Event \| Large Power Projects \| SOUTH AFRICA
Contingent Liabilities and Other Matters
Estimate of possible legal claim deemed unlikely								$ 10.0	R 142.8