Supplemental Guarantor Information Income statement (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Condensed financial statements
Sales	$ 3,820.5	$ 3,793.1	$ 6,688.5	$ 6,706.9
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Excise taxes	(735.3)	(701.8)	(1,271.8)	(1,166.9)
Net Sales	3,085.2	3,091.3	5,416.7	5,540.0
Cost of Goods Sold	(1,739.1)	(1,755.5)	(3,274.8)	(3,127.8)
Gross profit	1,346.1	1,335.8	2,141.9	2,412.2
Marketing, general and administrative expenses	(744.7)	(782.4)	(1,425.8)	(1,487.7)
Special items, net	(10.5)	(16.5)	304.3	(23.2)
Operating income (loss)	590.9	536.9	1,020.4	901.3
Interest income (expense), net	(76.7)	(89.2)	(159.9)	(185.8)
Other pension and postretirement benefits (costs), net	9.9	9.4	19.9	22.7
Other pension and postretirement benefits (costs), net		9.4	19.9	22.7
Other income (expense), net	(1.1)	3.1	0.0	2.9
Income tax benefit (expense)	(92.2)	(125.2)	(167.1)	(191.1)
Net Income (loss)	430.8	335.0	713.3	550.0
Net (income) loss attributable to noncontrolling interests	(6.7)	(5.1)	(11.1)	(11.6)
Net income (loss) attributable to Molson Coors Brewing Company	424.1	329.9	702.2	538.4
Comprehensive income (loss) attributable to Molson Coors Brewing Company	209.6	576.2	536.8	857.4
Parent Company [Member]
Condensed financial statements
Sales	0.0	8.3	4.9	15.3
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Excise taxes	0.0	0.0	0.0	0.0
Net Sales	0.0	8.3	4.9	15.3
Cost of Goods Sold	(0.5)	(1.0)	(1.0)	(1.0)
Gross profit	(0.5)	7.3	3.9	14.3
Marketing, general and administrative expenses	(60.9)	(68.2)	(131.1)	(135.9)
Special items, net	(0.4)	(0.3)	(0.4)	(0.8)
Equity income (loss) in subsidiaries	261.9	440.6	897.4	786.6
Operating income (loss)	200.1	379.4	769.8	664.2
Interest income (expense), net	(81.2)	(74.4)	(166.4)	(155.5)
Other pension and postretirement benefits (costs), net	0.0	0.0	0.0	0.0
Other income (expense), net	0.3	0.0	0.1	(8.2)
Income (loss) before income taxes	119.2	305.0	603.5	500.5
Income tax benefit (expense)	304.9	24.9	98.7	37.9
Net Income (loss)	424.1	329.9	702.2	538.4
Net (income) loss attributable to noncontrolling interests	0.0	0.0	0.0	0.0
Net income (loss) attributable to Molson Coors Brewing Company	424.1	329.9	702.2	538.4
Comprehensive income (loss) attributable to Molson Coors Brewing Company	209.6	576.2	536.8	857.4
Subsidiary Guarantors [Member]
Condensed financial statements
Sales	2,874.7	2,954.1	5,109.3	5,330.7
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Excise taxes	(406.4)	(411.5)	(707.8)	(737.2)
Net Sales	2,468.3	2,542.6	4,401.5	4,593.5
Cost of Goods Sold	(1,385.0)	(1,421.4)	(2,626.7)	(2,561.8)
Gross profit	1,083.3	1,121.2	1,774.8	2,031.7
Marketing, general and administrative expenses	(514.0)	(558.4)	(977.3)	(1,056.9)
Special items, net	(7.7)	(13.7)	313.7	(17.3)
Equity income (loss) in subsidiaries	79.2	(132.2)	(79.6)	(203.9)
Operating income (loss)	640.8	416.9	1,031.6	753.6
Interest income (expense), net	84.8	60.3	166.8	119.2
Other pension and postretirement benefits (costs), net	1.6	(2.0)	3.0	0.0
Other income (expense), net	(80.5)	94.9	(40.3)	111.6
Income (loss) before income taxes	646.7	570.1	1,161.1	984.4
Income tax benefit (expense)	(385.1)	(129.7)	(263.2)	(197.8)
Net Income (loss)	261.6	440.4	897.9	786.6
Net (income) loss attributable to noncontrolling interests	0.0	0.0	0.0	0.0
Net income (loss) attributable to Molson Coors Brewing Company	261.6	440.4	897.9	786.6
Comprehensive income (loss) attributable to Molson Coors Brewing Company	(30.7)	730.7	712.5	1,148.2
Subsidiary Non Guarantors [Member]
Condensed financial statements
Sales	1,079.7	973.2	1,822.3	1,623.2
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Excise taxes	(328.9)	(290.3)	(564.0)	(429.7)
Net Sales	750.8	682.9	1,258.3	1,193.5
Cost of Goods Sold	(485.8)	(463.7)	(885.5)	(805.1)
Gross profit	265.0	219.2	372.8	388.4
Marketing, general and administrative expenses	(171.5)	(167.7)	(327.0)	(317.1)
Special items, net	(2.4)	(2.5)	(9.0)	(5.1)
Equity income (loss) in subsidiaries	57.4	62.2	62.2	82.0
Operating income (loss)	148.5	111.2	99.0	148.2
Interest income (expense), net	(80.3)	(75.1)	(160.3)	(149.5)
Other pension and postretirement benefits (costs), net	8.3	11.4	16.9	22.7
Other income (expense), net	79.1	(91.8)	40.2	(100.5)
Income (loss) before income taxes	155.6	(44.3)	(4.2)	(79.1)
Income tax benefit (expense)	(12.0)	(20.4)	(2.6)	(31.2)
Net Income (loss)	143.6	(64.7)	(6.8)	(110.3)
Net (income) loss attributable to noncontrolling interests	(6.7)	(5.1)	(11.1)	(11.6)
Net income (loss) attributable to Molson Coors Brewing Company	136.9	(69.8)	(17.9)	(121.9)
Comprehensive income (loss) attributable to Molson Coors Brewing Company	(47.0)	92.0	(94.3)	82.8
Consolidated [Member]
Condensed financial statements
Sales	3,820.5	3,793.1	6,688.5	6,706.9
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Excise taxes	(735.3)	(701.8)	(1,271.8)	(1,166.9)
Net Sales	3,085.2	3,091.3	5,416.7	5,540.0
Cost of Goods Sold	(1,739.1)	(1,755.5)	(3,274.8)	(3,127.8)
Gross profit	1,346.1	1,335.8	2,141.9	2,412.2
Marketing, general and administrative expenses	(744.7)	(782.4)	(1,425.8)	(1,487.7)
Special items, net	(10.5)	(16.5)	304.3	(23.2)
Equity income (loss) in subsidiaries	0.0	0.0	0.0	0.0
Operating income (loss)	590.9	536.9	1,020.4	901.3
Interest income (expense), net	(76.7)	(89.2)	(159.9)	(185.8)
Other pension and postretirement benefits (costs), net	9.9	9.4	19.9	22.7
Other income (expense), net	(1.1)	3.1	0.0	2.9
Income (loss) before income taxes	523.0	460.2	880.4	741.1
Income tax benefit (expense)	(92.2)	(125.2)	(167.1)	(191.1)
Net Income (loss)	430.8	335.0	713.3	550.0
Net (income) loss attributable to noncontrolling interests	(6.7)	(5.1)	(11.1)	(11.6)
Net income (loss) attributable to Molson Coors Brewing Company	424.1	329.9	702.2	538.4
Comprehensive income (loss) attributable to Molson Coors Brewing Company	209.6	576.2	536.8	857.4
Consolidation, Eliminations [Member]
Condensed financial statements
Sales	(133.9)	(142.5)	(248.0)	(262.3)
CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS
Excise taxes	0.0	0.0	0.0	0.0
Net Sales	(133.9)	(142.5)	(248.0)	(262.3)
Cost of Goods Sold	132.2	130.6	238.4	240.1
Gross profit	(1.7)	(11.9)	(9.6)	(22.2)
Marketing, general and administrative expenses	1.7	11.9	9.6	22.2
Special items, net	0.0	0.0	0.0	0.0
Equity income (loss) in subsidiaries	(398.5)	(370.6)	(880.0)	(664.7)
Operating income (loss)	(398.5)	(370.6)	(880.0)	(664.7)
Interest income (expense), net	0.0	0.0	0.0	0.0
Other pension and postretirement benefits (costs), net	0.0	0.0	0.0	0.0
Other income (expense), net	0.0	0.0	0.0	0.0
Income (loss) before income taxes	(398.5)	(370.6)	(880.0)	(664.7)
Income tax benefit (expense)	0.0	0.0	0.0	0.0
Net Income (loss)	(398.5)	(370.6)	(880.0)	(664.7)
Net (income) loss attributable to noncontrolling interests	0.0	0.0	0.0	0.0
Net income (loss) attributable to Molson Coors Brewing Company	(398.5)	(370.6)	(880.0)	(664.7)
Comprehensive income (loss) attributable to Molson Coors Brewing Company	$ 77.7	$ (822.7)	$ (618.2)	$ (1,231.0)