Supplemental Guarantor Information Supplemental Narrative (Details) CAD in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Jul. 07, 2016 USD ($)	May 03, 2012 USD ($)	Oct. 06, 2010 CAD
Comprehensive income (loss) attributable to Molson Coors Brewing Company	$ 463,700,000	$ 143,100,000	$ 1,311,500,000	$ 599,100,000
Stockholders' Equity Attributable to Parent	12,488,200,000		12,488,200,000		$ 11,418,700,000
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	286,300,000	203,800,000	821,500,000	543,500,000
Net income (loss) including noncontrolling interests	286,100,000	203,800,000	822,300,000	541,200,000
Series A notes due 2017 CAD 500 million 3.95% [Member]
Debt Instrument, Face Amount | CAD								CAD 500.0
Debt instrument, interest rate percentage								3.95%
Subsidiary Guarantors [Member]
Income (Loss) from Equity Method Investments Consolidating	(78,700,000)	7,900,000	(294,800,000)	(123,400,000)	(347,600,000)
Comprehensive income (loss) attributable to Molson Coors Brewing Company	572,000,000	247,300,000	1,710,600,000	775,500,000
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	3,604,800,000		3,604,800,000		3,475,400,000
Stockholders' Equity Attributable to Parent	28,644,900,000		28,644,900,000		26,948,900,000
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	383,700,000	288,700,000	1,156,500,000	722,800,000	2,249,600,000
Net income (loss) including noncontrolling interests	383,700,000	288,700,000	1,156,500,000	722,800,000
Parent Company [Member]
Income (Loss) from Equity Method Investments Consolidating	383,500,000	292,800,000	1,156,300,000	737,100,000
Comprehensive income (loss) attributable to Molson Coors Brewing Company	463,700,000	143,100,000	1,311,500,000	599,100,000
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	24,216,300,000		24,216,300,000		22,506,300,000
Stockholders' Equity Attributable to Parent	12,488,200,000		12,488,200,000		11,418,700,000
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	280,000,000	202,500,000	804,600,000	537,500,000
Net income (loss) including noncontrolling interests	280,000,000	202,500,000	804,600,000	537,500,000
Senior Notes [Member]
Debt Instrument, Face Amount							$ 1,900,000,000
Senior Notes [Member] | Parent Company [Member] | Senior Notes Due 2017 $300M 2.0% [Member]
Debt Instrument, Face Amount							$ 300,000,000
Debt instrument, interest rate percentage							2.00%
Senior Notes [Member] | Parent Company [Member] | Senior Notes Due 2022 $500M 3.5% [Member]
Debt Instrument, Face Amount							$ 500,000,000
Debt instrument, interest rate percentage							3.50%
Senior Notes [Member] | Parent Company [Member] | Senior Notes Due 2042 $1.1B 5.0% [Member]
Debt Instrument, Face Amount							$ 1,100,000,000
Debt instrument, interest rate percentage							5.00%
Senior Notes [Member] | Parent Company [Member] | Senior Notes Due 2019 $500M 1.45% [Member]
Debt Instrument, Face Amount						$ 500,000,000
Debt instrument, interest rate percentage						1.45%
Senior Notes [Member] | Parent Company [Member] | Senior Notes Due 2021 $1B 2.1% [Member]
Debt Instrument, Face Amount						$ 1,000,000,000.0
Debt instrument, interest rate percentage						2.10%
Senior Notes [Member] | Parent Company [Member] | Senior Notes Due 2026 $2B 3.0% [Member]
Debt Instrument, Face Amount						$ 2,000,000,000
Debt instrument, interest rate percentage						3.00%
Senior Notes [Member] | Parent Company [Member] | Senior Notes Due 2046 $1.8B 4.2% [Member]
Debt Instrument, Face Amount						$ 1,800,000,000.0
Debt instrument, interest rate percentage						4.20%
Senior Notes [Member] | Parent Company [Member] | Senior Notes Due 2024 EUR800M 1.25% [Member]
Debt Instrument, Face Amount						$ 800,000,000
Debt instrument, interest rate percentage						1.25%
Consolidation, Eliminations [Member]
Income (Loss) from Equity Method Investments Consolidating	(375,700,000)	(392,800,000)	(1,012,700,000)	(943,000,000)	(1,775,100,000)
Comprehensive income (loss) attributable to Molson Coors Brewing Company	(644,000,000)	(333,600,000)	(1,855,800,000)	(860,800,000)
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(32,217,000,000)		(32,217,000,000)		(30,382,600,000)
Stockholders' Equity Attributable to Parent	(32,217,000,000)		(32,217,000,000)		(30,382,600,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(375,700,000)	(392,800,000)	(1,012,700,000)	(943,000,000)	(1,775,100,000)
Net income (loss) including noncontrolling interests	$ (375,700,000)	(392,800,000)	$ (1,012,700,000)	(943,000,000)
Scenario, Previously Reported [Member] | Subsidiary Guarantors [Member]
Income (Loss) from Equity Method Investments Consolidating		(19,400,000)		(223,700,000)	(21,800,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		261,400,000		622,500,000	2,575,400,000
Scenario, Previously Reported [Member] | Consolidation, Eliminations [Member]
Income (Loss) from Equity Method Investments Consolidating		(365,500,000)		(842,700,000)	(2,100,900,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest		$ (365,500,000)		$ (842,700,000)	$ (2,100,900,000)