CONSOLIDATED STATEMENTS OF CHANGES IN OWNERS' EQUITY AND SERIES A PREFERRED STOCK (Unaudited) - USD ($) shares in Thousands, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Retained Earnings (Accumulated Deficit) [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Shares [Member]	Noncontrolling Interests [Member]	Series A Preferred Stock [Member]	Series A Preferred Stock [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]
Balance at Dec. 31, 2019	$ 8,442.9		$ 0.2	$ 5,221.2		$ (339.6)	$ 92.5	$ (53.5)	$ 3,522.1
Balance (in shares) at Dec. 31, 2019			232,844					1,010
Series A Preferred Stock at Dec. 31, 2019										$ 278.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation on equity grants	49.5			49.5
Distribution equivalent rights	(3.5)			(3.5)
Shares issued under compensation program (in shares)			892
Shares and units tendered for tax withholding obligations	(5.5)							$ (5.5)
Shares and units tendered for tax withholding obligations (in shares)			(218)					218
Series A Preferred Stock dividends
Preferred stock dividends	(68.8)					(68.8)
Dividends in excess of retained earnings				(68.8)		68.8
Deemed dividends - accretion of beneficial conversion feature	(27.7)			(27.7)						27.7
Common stock dividends
Common stock dividends	(259.0)					(259.0)
Dividends in excess of retained earnings				(259.0)		259.0
Distributions to noncontrolling interests	(322.9)								(322.9)
Contributions from noncontrolling interests	33.3								33.3
Non-cash allocation to noncontrolling interests	27.5								27.5
Other comprehensive income (loss)	(183.3)						(183.3)
Net income (loss)	(1,471.0)					(1,587.5)			116.5
Balance at Sep. 30, 2020	6,211.5		$ 0.2	4,911.7		(1,927.1)	(90.8)	$ (59.0)	3,376.5
Balance (in shares) at Sep. 30, 2020			233,518					1,228
Series A Preferred Stock at Sep. 30, 2020										306.5
Balance at Dec. 31, 2019	8,442.9		$ 0.2	5,221.2		(339.6)	92.5	$ (53.5)	3,522.1
Balance at Jun. 30, 2020	6,269.1		$ 0.2	4,949.1		(1,996.4)	21.6	$ (56.9)	3,351.5
Balance (in shares) at Jun. 30, 2020			233,177					1,116
Series A Preferred Stock at Jun. 30, 2020										297.0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation on equity grants	16.4			16.4
Distribution equivalent rights	1.9			1.9
Shares issued under compensation program (in shares)			453
Shares and units tendered for tax withholding obligations	(2.1)							$ (2.1)
Shares and units tendered for tax withholding obligations (in shares)			(112)					112
Series A Preferred Stock dividends
Preferred stock dividends	(22.9)					(22.9)
Dividends in excess of retained earnings				(22.9)		22.9
Deemed dividends - accretion of beneficial conversion feature	(9.5)			(9.5)						9.5
Common stock dividends
Common stock dividends	(23.3)					(23.3)
Dividends in excess of retained earnings				(23.3)		23.3
Distributions to noncontrolling interests	(113.1)								(113.1)
Contributions from noncontrolling interests	7.7								7.7
Non-cash allocation to noncontrolling interests	27.5								27.5
Other comprehensive income (loss)	(112.4)						(112.4)
Net income (loss)	172.2					69.3			102.9
Balance at Sep. 30, 2020	6,211.5		$ 0.2	4,911.7		(1,927.1)	(90.8)	$ (59.0)	3,376.5
Balance (in shares) at Sep. 30, 2020			233,518					1,228
Series A Preferred Stock at Sep. 30, 2020										306.5
Balance at Jun. 30, 2020	6,269.1		$ 0.2	4,949.1		(1,996.4)	21.6	$ (56.9)	3,351.5
Balance at Dec. 31, 2020	5,903.2	$ (448.3)	$ 0.2	4,839.9	$ (448.3)	(1,893.5)	(141.8)	$ (150.9)	3,249.3		$ 448.3
Balance (in shares) at Dec. 31, 2020			228,062					6,731
Series A Preferred Stock at Dec. 31, 2020										301.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation on equity grants	44.6			44.6
Distribution equivalent rights	(2.4)			(2.4)
Shares issued under compensation program (in shares)			1,294
Shares and units tendered for tax withholding obligations	(13.1)							$ (13.1)
Shares and units tendered for tax withholding obligations (in shares)			(393)					393
Series A Preferred Stock dividends
Preferred stock dividends	(65.5)					(65.5)
Dividends in excess of retained earnings				(65.5)		65.5
Common stock dividends
Common stock dividends	(68.6)					(68.6)
Dividends in excess of retained earnings				(68.6)		68.6
Distributions to noncontrolling interests	(334.2)								(334.2)
Contributions from noncontrolling interests	13.2								13.2
Other comprehensive income (loss)	(300.3)						(300.3)
Net income (loss)	671.3					384.8			286.5
Balance at Sep. 30, 2021	5,399.9		$ 0.2	4,299.7		(1,508.7)	(442.1)	$ (164.0)	3,214.8
Balance (in shares) at Sep. 30, 2021			228,963					7,124
Series A Preferred Stock at Sep. 30, 2021										749.7
Balance at Dec. 31, 2020	5,903.2	$ (448.3)	$ 0.2	4,839.9	$ (448.3)	(1,893.5)	(141.8)	$ (150.9)	3,249.3		$ 448.3
Balance at Jun. 30, 2021	5,396.5		$ 0.2	4,330.8		(1,690.9)	(294.4)	$ (159.5)	3,210.3
Balance (in shares) at Jun. 30, 2021			228,655					7,016
Series A Preferred Stock at Jun. 30, 2021										749.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation on equity grants	14.7			14.7
Distribution equivalent rights	(1.1)			(1.1)
Shares issued under compensation program (in shares)			416
Shares and units tendered for tax withholding obligations	(4.5)							$ (4.5)
Shares and units tendered for tax withholding obligations (in shares)			(108)					108
Series A Preferred Stock dividends
Preferred stock dividends	(21.8)					(21.8)
Dividends in excess of retained earnings				(21.8)		21.8
Common stock dividends
Common stock dividends	(22.9)					(22.9)
Dividends in excess of retained earnings				(22.9)		22.9
Distributions to noncontrolling interests	(110.4)								(110.4)
Contributions from noncontrolling interests	9.1								9.1
Other comprehensive income (loss)	(147.7)						(147.7)
Net income (loss)	288.0					182.2			105.8
Balance at Sep. 30, 2021	5,399.9		$ 0.2	4,299.7		(1,508.7)	(442.1)	$ (164.0)	3,214.8
Balance (in shares) at Sep. 30, 2021			228,963					7,124
Series A Preferred Stock at Sep. 30, 2021										$ 749.7
Balance at Jun. 30, 2021	$ 5,396.5		$ 0.2	$ 4,330.8		$ (1,690.9)	$ (294.4)	$ (159.5)	$ 3,210.3