Derivative Instruments and Hedging Activities - Fair Value Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	$ 4.0	$ 13.3
Derivative Liabilities	(275.4)	(112.7)
Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	41.7	9.4
Derivative Liabilities	(58.8)	(47.9)
Cross currency swaps \| Designated as hedging instruments \| Net investment hedging
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Notional amount	400.0	900.0
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Notional amount	400.0	900.0
Interest rate swaps \| Designated as hedging instruments \| Cash flow hedging
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Notional amount	1,500.0	1,500.0
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Notional amount	1,500.0	1,500.0
Foreign currency forwards \| Designated as hedging instruments \| Cash flow hedging
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Notional amount	169.5	237.9
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Notional amount	169.5	237.9
Commodity swaps \| Not designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Notional amount	938.3	598.4
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Notional amount	938.3	598.4
Commodity options \| Not designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Notional amount		18.4
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Notional amount		18.4
Warrants \| Not designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Notional amount	51.8	53.1
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Notional amount	51.8	53.1
Other current assets \| Cross currency swaps \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	0.0	1.8
Other current assets \| Interest rate swaps \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	0.0
Other current assets \| Foreign currency forwards \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	3.1	1.9
Other current assets \| Commodity swaps \| Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	16.1	5.7
Other current assets \| Commodity options \| Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets		0.0
Accounts payable and other current liabilities \| Cross currency swaps \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	(7.0)	0.0
Accounts payable and other current liabilities \| Interest rate swaps \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	(53.1)
Accounts payable and other current liabilities \| Foreign currency forwards \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	(0.5)	(0.8)
Accounts payable and other current liabilities \| Commodity swaps \| Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	(47.2)	(36.4)
Accounts payable and other current liabilities \| Commodity options \| Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities		0.0
Other non-current assets \| Cross currency swaps \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	0.0	8.2
Other non-current assets \| Interest rate swaps \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	0.0	0.0
Other non-current assets \| Foreign currency forwards \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	0.9	1.4
Other non-current assets \| Commodity swaps \| Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	25.1	1.0
Other non-current assets \| Warrants \| Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Assets	0.5	2.7
Other liabilities \| Cross currency swaps \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	0.0	0.0
Other liabilities \| Interest rate swaps \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	(214.3)	(111.5)
Other liabilities \| Foreign currency forwards \| Designated as hedging instruments
Derivatives Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	(0.5)	(0.4)
Other liabilities \| Commodity swaps \| Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	(11.6)	(11.5)
Other liabilities \| Warrants \| Not designated as hedging instruments
Derivatives Not Designated as Hedging Instrument, Item List [Abstract]
Derivative Liabilities	$ 0.0	$ 0.0

-- None. No documentation exists for this element. --

No definition available.

Name:	tap_DerivativesDesignatedAsHedgingInstrumentItemListAbstract
Namespace Prefix:	tap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	tap_DerivativesNotDesignatedAsHedgingInstrumentItemListAbstract
Namespace Prefix:	tap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=118948506&loc=SL51823488-111719

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

+ Details

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

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=118948506&loc=SL51823488-111719

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226000-175313

+ Details

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

- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

+ Details

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

- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as a liability.

+ References

+ Details

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

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

+ Details

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_DesignatedAsHedgingInstrumentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CrossCurrencyInterestRateContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_NetInvestmentHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis=us-gaap_CashFlowHedgingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_ForeignExchangeForwardMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CommodityOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_WarrantMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

- Details

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