Analysis of Net Debt - Schedule of Liquidity and Capital Resources Related to Cash Generation and Changes in Our Cash and Cash Equivalents Position (Detail) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Cash Generation And Changes In Our Cash And Cash Equivalents Position [abstract]
Net cash inflow from operating activities	€ 1,899	€ 2,189	€ 2,340
Net cash outflow from investing activities	(1,592)	(2,685)	(735)
Net cash (outflow)/inflow from financing activities	(113)	343	(1,732)
Increase/(decrease) in cash and cash equivalents	194	(153)	(127)
Cash and cash equivalents at 1 January	2,135	2,449	2,518
Effect of exchange rate changes	17	(161)	58
Cash and cash equivalents at 31 December	2,346	2,135	2,449
Bank overdrafts	(113)	(71)	(78)
Borrowings	(9,203)	(7,910)	(7,712)
Derivative financial instruments	(14)	50	44
Total liabilities from financing activities	(9,330)	(7,931)	(7,746)
Group net debt	(6,984)	(5,796)	(5,297)	€ (6,618)
Cash at bank and in hand reclassified as held for sale (note 24)		(20)
Bank overdrafts reclassified as held for sale (note 25)		5
Net debt excluding cash and debt reclassified as held for sale	€ (6,984)	€ (5,811)	€ (5,297)

Bank overdraft included in loans and borrowings.

No definition available.

Name:	crh_BankOverdraftIncludedInLoansAndBorrowings
Namespace Prefix:	crh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Bank overdrafts reclassified as held for sale.

+ References

No definition available.

+ Details

Name:	crh_BankOverdraftsReclassifiedAsHeldForSale
Namespace Prefix:	crh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Borrowings excluding bank overdrafts.

+ References

No definition available.

+ Details

Name:	crh_BorrowingsExcludingBankOverdrafts
Namespace Prefix:	crh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cash reclassified as held for sale.

+ References

No definition available.

+ Details

Name:	crh_CashReclassifiedAsHeldForSale
Namespace Prefix:	crh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The net amount of total derivative financial assets less total derivative financial liabilities

+ References

No definition available.

+ Details

Name:	crh_DerivativeFinancialAssetsLiabilitiesNet
Namespace Prefix:	crh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Disclosure of cash generation and changes in our cash and cash equivalents position.

+ References

No definition available.

+ Details

Name:	crh_DisclosureOfCashGenerationAndChangesInOurCashAndCashEquivalentsPositionAbstract
Namespace Prefix:	crh_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Net debt excluding cash and debt reclassified as held for sale.

+ References

No definition available.

+ Details

Name:	crh_NetDebtExcludingCashAndDebtReclassifiedAsHeldForSale
Namespace Prefix:	crh_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of cash and cash equivalents in the statement of cash flows when different from the amount of cash and cash equivalents in the statement of financial position. [Refer: Cash and cash equivalents]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_45&doctype=Standard
-URIDate 2018-03-16

+ Details

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

- Definition

The cash flows from (used in) financing activities, which are activities that result in changes in the size and composition of the contributed equity and borrowings of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 10
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_10&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 50
-Subparagraph d
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_50_d&doctype=Standard
-URIDate 2018-03-16

+ Details

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

- Definition

The cash flows from (used in) investing activities, which are the acquisition and disposal of long-term assets and other investments not included in cash equivalents.

+ References

+ Details

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

- Definition

The cash flows from (used in) operating activities, which are the principal revenue-producing activities of the entity and other activities that are not investing or financing activities. [Refer: Revenue]

+ References

+ Details

Name:	ifrs-full_CashFlowsFromUsedInOperatingActivities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

The effect of exchange rate changes on cash and cash equivalents held or due in a foreign currency. [Refer: Cash and cash equivalents]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 25
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_25&doctype=Standard
-URIDate 2018-03-16

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 28
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_28&doctype=Standard
-URIDate 2018-03-16

+ Details

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

- Definition

The increase (decrease) in cash and cash equivalents before the effect of exchange rate changes on cash and cash equivalents held in foreign currencies. [Refer: Cash and cash equivalents; Effect of exchange rate changes on cash and cash equivalents]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 45
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_45&doctype=Standard
-URIDate 2018-03-16

+ Details

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

- Definition

The amount of liabilities for which cash flows were, or future cash flows will be, classified in the statement of cash flows as cash flows from financing activities. [Refer: Cash flows from (used in) financing activities; Liabilities]

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 7
-IssueDate 2018-01-01
-Paragraph 44D
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=7&date=2018-03-01&anchor=para_44D&doctype=Standard
-URIDate 2018-03-16

+ Details

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

- Definition

The amount of net debt of the entity.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2018-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_112_c&doctype=Standard
-URIDate 2018-03-16

+ Details

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