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, 2018	$ 13,735.8	$ 0.0	$ 2.0	$ 103.2	$ 557.6	$ 6,773.1	$ 7,692.9	$ (1,150.0)	$ (471.4)	$ 228.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plan	(8.2)					(8.2)
Amortization of share-based compensation	11.3					11.3
Net income (loss) including noncontrolling interests	149.1						151.4			(2.3)
Other comprehensive income (loss), net of tax	42.3							42.1		0.2
Initial Application Period Cumulative Effect Transition for Accounting Standards Update 2016-02	32.0						32.0
Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect	0.0						74.8	(74.8)
Contributions from noncontrolling interests	14.5									14.5
Dividends declared and paid	(88.7)						(88.7)			0.0
Balance at Mar. 31, 2019	13,888.1	0.0	2.0	103.2	557.6	6,776.2	7,862.4	(1,182.7)	(471.4)	240.8
Balance at Dec. 31, 2019	13,673.1	0.0	2.1	102.5	557.8	6,773.6	7,617.0	(1,162.2)	(471.4)	253.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued under equity compensation plan	1.2					1.2
Amortization of share-based compensation	5.9					5.9
Acquisition of business and purchase of noncontrolling interest	(0.1)									(0.1)
Net income (loss) including noncontrolling interests	(115.4)						(117.0)			1.6
Other comprehensive income (loss), net of tax	(502.0)							(499.1)		(2.9)
Contributions from noncontrolling interests	8.6									8.6
Distributions and dividends to noncontrolling interests	(1.5)									(1.5)
Dividends declared and paid	(123.8)						(123.8)			0.0
Balance at Mar. 31, 2020	$ 12,946.0	$ 0.0	$ 2.1	$ 102.5	$ 557.8	$ 6,780.7	$ 7,376.2	$ (1,661.3)	$ (471.4)	$ 259.4