CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY AND NONCONTROLLING INTERESTS - USD ($) $ in Millions	Total	Class A common stock, voting [Member]	Common Class B [Member]	Exchangeable shares issued, Class A	Exchangeable shares issued, Class B	Paid-in capital	Retained earnings	AOCI Attributable to Parent [Member]	Common stock held in treasury, Class B	Noncontrolling interest
Balance at Dec. 31, 2016	$ 11,621.7	$ 0.0	$ 2.0	$ 108.1	$ 571.2	$ 6,635.3	$ 6,145.3	$ (1,571.8)	$ (471.4)	$ 203.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchange of shares	0.0			(0.4)	(18.0)	18.4
Shares issued under equity compensation plan	(22.4)					(22.4)
Amortization of share-based compensation	45.3					45.3
Acquisition of business and purchase of noncontrolling interest	1.6									1.6
Net income (loss) including noncontrolling interests	843.1						825.4			17.7
Other comprehensive income (loss), net of tax	503.3							500.9		2.4
Dividends declared and paid	(281.2)						(264.9)			(16.3)
Balance at Sep. 30, 2017	12,711.4	0.0	2.0	107.7	553.2	6,676.6	6,705.8	(1,070.9)	(471.4)	208.4
Balance at Dec. 31, 2017	13,435.0	0.0	2.0	107.7	553.2	6,688.5	7,206.1	(860.0)	(471.4)	208.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exchange of shares	0.0			(4.3)	4.2	0.1
Shares issued under equity compensation plan	(6.3)					(6.3)
Amortization of share-based compensation	33.6					33.6
Acquisition of business and purchase of noncontrolling interest	(0.2)									(0.2)
Net income (loss) including noncontrolling interests	1,058.9						1,040.5			18.4
Other comprehensive income (loss), net of tax	(137.5)							(136.4)		(1.1)
Initial Application Period Cumulative Effect Transition for Accounting Standards Update 2014-09	(27.8)						(27.8)
Proceeds from (Payments to) Noncontrolling Interests	14.4									14.4
Dividends declared and paid	(280.1)						(265.6)			(14.5)
Balance at Sep. 30, 2018	$ 14,090.0	$ 0.0	$ 2.0	$ 103.4	$ 557.4	$ 6,715.9	$ 7,953.2	$ (996.4)	$ (471.4)	$ 225.9