Antidilutive securities excluded from computation of earning per share amount.

No definition available.

Name:	cx_AntidilutiveSecuritiesExcludedFromComputationOfEarningPerShareAmount
Namespace Prefix:	cx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Average contract life of foreign exchange forward program.

+ References

No definition available.

+ Details

Name:	cx_AverageContractLifeOfForeignExchangeForwardProgram
Namespace Prefix:	cx_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Derivative maturity date month and year.

+ References

No definition available.

+ Details

Name:	cx_DerivativeMaturityDateMonthAndYear
Namespace Prefix:	cx_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity forward contract settled by shares.

+ References

No definition available.

+ Details

Name:	cx_EquityForwardContractSettledByShares
Namespace Prefix:	cx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Increase in variable common stock issued to preserve anti-dilutive rights of note holders.

+ References

No definition available.

+ Details

Name:	cx_IncreaseInVariableCommonStockIssuedToPreserveAntidilutiveRightsOfNoteHolders
Namespace Prefix:	cx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Notional amount annual interest rate.

+ References

No definition available.

+ Details

Name:	cx_NotionalAmountAnnualInterestRate
Namespace Prefix:	cx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage amendment of notional amount of capped calls option.

+ References

No definition available.

+ Details

Name:	cx_PercentageAmendmentOfNotionalAmountOfCappedCallsOption
Namespace Prefix:	cx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of notional amount of entity's overall currency and interest rate positions.

+ References

No definition available.

+ Details

Name:	cx_PercentageOfNotionalAmountOfEntitysOverallCurrencyAndInterestRatePositions
Namespace Prefix:	cx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The interest rate on borrowings. [Refer: Borrowings]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 7
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_7&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_BorrowingsInterestRate
Namespace Prefix:	ifrs-full_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfFinancialInstrumentsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The estimated cash flows of financial assets reclassified out of the available-for-sale category. [Refer: Financial assets available-for-sale]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Expiry date 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 12A
-Subparagraph f
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-02&anchor=para_12A_f&doctype=Standard&book=B
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_EstimatedCashFlowsOfFinancialAssetsReclassifiedOutOfAvailableforsaleFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The fair value of financial assets. [Refer: At fair value [member]; Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 25
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_25&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_FinancialAssetsAtFairValue
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of financial assets that are measured at fair value and for which gains (losses) are recognised in profit or loss. A financial asset shall be measured at fair value through profit or loss unless it is measured at amortised cost or at fair value through other comprehensive income. A gain (loss) on a financial asset measured at fair value shall be recognised in profit or loss unless it is part of a hedging relationship, it is an investment in an equity instrument for which the entity has elected to present gains and losses in other comprehensive income or it is a financial asset measured at fair value through other comprehensive income. [Refer: At fair value [member]; Financial assets]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 8
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_8_a&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLoss
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of financial assets mandatorily measured at fair value through profit or loss in accordance with IFRS 9. [Refer: Financial assets at fair value through profit or loss]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 8
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_8_a&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_FinancialAssetsAtFairValueThroughProfitOrLossMandatorilyMeasuredAtFairValue
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The gain (loss) recognised on designation of a financial instrument, or a proportion of it, as measured at fair value through profit or loss, because a credit derivative is used to manage the credit risk of that financial instrument. [Refer: Credit risk [member]; Derivatives [member]; Financial instruments, class [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 24G
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24G_b&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_GainLossOnDesignationOfFinancialInstrumentAsMeasuredAtFairValueThroughProfitOrLossBecauseCreditDerivativeIsUsedToManageCreditRisk
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The gain (loss) recognised on derecognition of financial instruments whose fair value previously could not be reliably measured. [Refer: Financial instruments, class [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 30
-Subparagraph e
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_30_e&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_GainLossRecognisedOnFinancialInstrumentsWhoseFairValuePreviouslyCouldNotBeReliablyMeasured
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The increase (decrease) in the provision for unearned premiums. [Refer: Unearned premiums]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 85
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_85&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_IncreaseDecreaseInProvisionForUnearnedPremium
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The increase (decrease) in equity resulting from the conversion of convertible instruments.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 106
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_106_d&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_IncreaseDecreaseThroughConversionOfConvertibleInstruments
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The net gain arising from foreign exchange differences. [Refer: Foreign exchange gain (loss)]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 21
-IssueDate 2017-01-01
-Paragraph 52
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=21&date=2017-03-01&anchor=para_52_a&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_NetForeignExchangeGain
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The net loss arising from foreign exchange differences. [Refer: Foreign exchange gain (loss)]

+ References

+ Details

Name:	ifrs-full_NetForeignExchangeLoss
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The nominal or face amount of a financial instrument, used to calculate payments made on that instrument.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_NotionalAmount
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Prices specified in forward agreements to purchase financial assets for cash.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph B11D
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_B11D_b&doctype=Appendix&seq=2
-URIDate 2017-03-09

+ Details

Name:	ifrs-full_PricesSpecifiedInForwardAgreementsToPurchaseFinancialAssetsForCash
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	ifrs-full_ContinuingInvolvementInDerecognisedFinancialAssetsByTypeOfInstrumentAxis=ifrs-full_PurchasedCallOptionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfShareCapitalAxis=cx_AmericanDepositarySharesMaturingOnMarchTwoThousandSixteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfShareCapitalAxis=cx_AmericanDepositarySharesMaturingOnMarchTwoThousandEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_BorrowingsByNameAxis=cx_TwoThousandEighteenConvertibleNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialLiabilitiesAxis=cx_MandatoryConvertibleSecuritiesTwoThousandNineteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_HedgingInstrumentsAxis=cx_FuelPriceForwardContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_HedgingInstrumentsAxis=cx_CoalPriceForwardContractsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=cx_NetInvestmentHedgesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_CategoriesOfFinancialAssetsAxis=ifrs-full_ForwardContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_RangeAxis=ifrs-full_TopOfRangeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=cx_ForeignExchangeForwardsRelatedToForecastedTransactionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ifrs-full_EquityInvestmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_NonadjustingEventsAfterReportingPeriodAxis=ifrs-full_MajorBusinessCombinationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ifrs-full_InterestRateSwapContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Financial Instruments - Additional Information - Derivative Financial Instruments (Detail) $ in Millions		1 Months Ended		12 Months Ended
	Mar. 15, 2016	Aug. 31, 2016 shares	Oct. 31, 2015 MXN ($)	Dec. 31, 2017 USD ($) shares	Dec. 31, 2017 MXN ($) shares	Dec. 31, 2016 USD ($) shares	Dec. 31, 2016 MXN ($) shares	Dec. 31, 2015 USD ($)	Dec. 31, 2015 MXN ($)	Dec. 31, 2017 MXN ($)	Mar. 31, 2017 USD ($)	Mar. 30, 2017 shares	Dec. 31, 2016 MXN ($) shares	Oct. 31, 2016 USD ($)	Mar. 31, 2016 shares	Dec. 31, 2015 MXN ($)	Mar. 26, 2015 shares	Mar. 15, 2011 shares
Disclosure of detailed information about financial instruments [line items]
Gains and (losses) related to recognition of changes in fair values of the derivative instruments				$ 9,000,000	$ 161.0	$ 17,000,000	$ 317.0	$ (173,000,000)	$ (2,981.0)
Financial assets at estimated fair value				73,000,000		64,000,000
Increase (decrease) through conversion of convertible instruments, equity					5,729.0				$ 5,051.0
Call capped transaction subject to antidilution adjustments, Shares \| shares												258,000,000			297,000,000		297,000,000
Capped call options [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets at fair value through profit or loss						66,000,000							$ 1,368.0
Financial assets at fair value through profit or loss, mandatorily measured at fair value				37,000,000		$ 44,000,000		(228,000,000)		$ 725.0			$ 818.0			$ (3,928.0)
Call capped transaction subject to antidilution adjustments, Shares \| shares						3,960,000							3,960,000					194,000,000
Call capped transaction subject to antidilution adjustments, Shares \| shares						8.57	8.57
Capped call options [Member] \| American Depositary Shares Maturing on March 2016 [Member]
Disclosure of detailed information about financial instruments [line items]
Call capped transaction subject to antidilution adjustments, Shares \| shares																		114,000,000
Call capped transaction subject to antidilution adjustments, Shares \| shares						8.57	8.57
Capped call options [Member] \| American Depositary Shares Maturing on March 2018 [Member]
Disclosure of detailed information about financial instruments [line items]
Amount received by CEMEX								$ 44,000,000
Call capped transaction subject to antidilution adjustments, Shares \| shares		71,000,000																80,000,000
Call capped transaction subject to antidilution adjustments, Shares \| shares						5.27	5.27
Aggregate premium, Amount						$ 222,000,000
Notional amount percentage of capped call								44.20%	44.20%
Notional amount percentage of capped call, expired out of money	55.80%
Capped call options [Member] \| 2018 Convertible Notes [Member] \| American Depositary Shares Maturing on March 2018 [Member]
Disclosure of detailed information about financial instruments [line items]
Percentage amendment of notional amount		58.30%
Mandatory Convertible Securities 2019 [Member]
Disclosure of detailed information about financial instruments [line items]
Increase (decrease) through conversion of convertible instruments, equity				20,000,000	393.0	40,000,000	$ 829.0
Financial assets at fair value through profit or loss, mandatorily measured at fair value				19,000,000		(29,000,000)		$ 18,000,000		359.0			$ (545.0)			310.0
Fuel Price Forward Contracts [Member]
Disclosure of detailed information about financial instruments [line items]
Derivative financial instrument, Notional amount				46,000,000		44,000,000				904.0			912.0
Financial assets at estimated fair value				10,000,000		7,000,000				197.0			145.0
Gain (loss) due to changes in estimated fair value				3,000,000	57.0	7,000,000	145.0	(3,000,000)	$ (52.0)
Coal Price Forward Contracts [Member]
Disclosure of detailed information about financial instruments [line items]
Derivative financial instrument, Notional amount				26,000,000		33,000,000				511.0			684.0
Financial assets at estimated fair value				10,000,000		8,000,000				197.0			166.0
Gain (loss) due to changes in estimated fair value				1,000,000	19.0	8,000,000	166.0
Net Investment Hedges [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets at estimated fair value				47,000,000		0
Net Investment Hedges [Member] \| Forward Contract [Member]
Disclosure of detailed information about financial instruments [line items]
Derivative financial instrument, Notional amount				1,160,000,000
Net foreign exchange gain				$ 6,000,000	$ 110.0
Average contract life of foreign exchange forward program				1 year	1 year
Net Investment Hedges [Member] \| Top of range [member] \| Forward Contract [Member]
Disclosure of detailed information about financial instruments [line items]
Derivative financial instrument, Notional amount											$ 1,250,000,000
Foreign exchange forwards related to forecasted transactions [member]
Disclosure of detailed information about financial instruments [line items]
Financial assets at estimated fair value				$ 3,000,000		0
Foreign exchange forwards related to forecasted transactions [member] \| Forward Contract [Member]
Disclosure of detailed information about financial instruments [line items]
Net foreign exchange gain						10,000,000	$ 186.0	26,000,000	$ 448.0
Net foreign exchange loss				17,000,000	$ 337.0
Equity Investments [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets at fair value through profit or loss				$ 24,000,000		2,000,000		15,000,000		463.0			30.0			258.0
Interest rate swap maturity date			2016-10	2019-03	2019-03
Forward contract to be settled in cash \| shares				31,400,000	31,400,000
Amount received by CEMEX			$ 59.5
Estimated cash flows of financial assets reclassified out of available-for-sale financial assets			$ 59.5
Equity Investments [Member] \| Major business combination [member]
Disclosure of detailed information about financial instruments [line items]
Amount received by CEMEX														$ 4,000,000
Interest Rate Swap Contract [Member]
Disclosure of detailed information about financial instruments [line items]
Financial assets at fair value through profit or loss				$ 6,000,000		6,000,000		$ 4,000,000		114.0			112.0			$ 69.0
Interest rate swap maturity date				2022-09	2022-09
Financial assets at estimated fair value				$ 16,000,000		$ 23,000,000				$ 314.0			$ 477.0
Borrowings, interest rate				5.40%						5.40%