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	33.1			33.1
Distribution equivalent rights	(5.6)			(5.6)
Shares issued under compensation program (in shares)			439
Shares and units tendered for tax withholding obligations	(3.4)							$ (3.4)
Shares and units tendered for tax withholding obligations (in shares)			(106)					106
Series A Preferred Stock dividends
Preferred stock dividends	(45.8)					(45.8)
Dividends in excess of retained earnings				(45.8)		45.8
Deemed dividends - accretion of beneficial conversion feature	(18.2)			(18.2)						18.2
Common stock dividends
Common stock dividends	(235.6)					(235.6)
Dividends in excess of retained earnings				(235.6)		235.6
Distributions to noncontrolling interests	(209.9)								(209.9)
Contributions from noncontrolling interests	25.7								25.7
Other comprehensive income (loss)	(70.9)						(70.9)
Net income (loss)	(1,643.2)					(1,656.8)			13.6
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
Balance at Dec. 31, 2019	8,442.9		$ 0.2	5,221.2		(339.6)	92.5	$ (53.5)	3,522.1
Balance at Mar. 31, 2020	6,372.5		$ 0.2	4,991.7		(2,077.4)	168.4	$ (56.6)	3,346.2
Balance (in shares) at Mar. 31, 2020			233,110					1,092
Series A Preferred Stock at Mar. 31, 2020										287.8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation on equity grants	16.1			16.1
Distribution equivalent rights	(3.3)			(3.3)
Shares issued under compensation program (in shares)			91
Shares and units tendered for tax withholding obligations	(0.3)							$ (0.3)
Shares and units tendered for tax withholding obligations (in shares)			(24)					24
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	(9.2)			(9.2)						9.2
Common stock dividends
Common stock dividends	(23.3)					(23.3)
Dividends in excess of retained earnings				(23.3)		23.3
Distributions to noncontrolling interests	(105.9)								(105.9)
Contributions from noncontrolling interests	15.1								15.1
Other comprehensive income (loss)	(146.8)						(146.8)
Net income (loss)	177.1					81.0			96.1
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
Balance at Mar. 31, 2020	6,372.5		$ 0.2	4,991.7		(2,077.4)	168.4	$ (56.6)	3,346.2
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	29.9			29.9
Distribution equivalent rights	(1.3)			(1.3)
Shares issued under compensation program (in shares)			878
Shares and units tendered for tax withholding obligations	(8.6)							$ (8.6)
Shares and units tendered for tax withholding obligations (in shares)			(285)					285
Series A Preferred Stock dividends
Preferred stock dividends	(43.7)					(43.7)
Dividends in excess of retained earnings				(43.7)		43.7
Common stock dividends
Common stock dividends	(45.7)					(45.7)
Dividends in excess of retained earnings				(45.7)		45.7
Distributions to noncontrolling interests	(223.8)								(223.8)
Contributions from noncontrolling interests	4.1								4.1
Other comprehensive income (loss)	(152.6)						(152.6)
Net income (loss)	383.3					202.6			180.7
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
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 Mar. 31, 2021	5,522.4		$ 0.2	4,361.5		(1,747.1)	(158.4)	$ (159.5)	3,225.7
Balance (in shares) at Mar. 31, 2021			228,655					7,016
Series A Preferred Stock at Mar. 31, 2021										749.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Compensation on equity grants	15.0			15.0
Distribution equivalent rights	(1.0)			(1.0)
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	(116.7)								(116.7)
Contributions from noncontrolling interests	2.1								2.1
Other comprehensive income (loss)	(136.0)						(136.0)
Net income (loss)	155.4					56.2			99.2
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
Balance at Mar. 31, 2021	$ 5,522.4		$ 0.2	$ 4,361.5		$ (1,747.1)	$ (158.4)	$ (159.5)	$ 3,225.7