CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (DEFICIT) (unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interests [Member]
Cumulative effect of adopting new hedging standard	$ 0.8				$ (0.8)	$ 0.8
Beginning Balance at Dec. 31, 2017		$ 3.2	$ 2,884.8	$ (5.4)	(2,877.0)	(50.2)	$ 345.2
Share-based compensation			6.3
Purchase of treasury stock				(1.0)
Net income	85.3				85.3
Change in accumulated other comprehensive income (loss)	(17.4)					(17.4)
Net income attributable to noncontrolling interests	31.8						31.8
Net distributions to noncontrolling interests							(34.8)
Ending Balance at Jun. 30, 2018	370.8	3.2	2,891.1	(6.4)	(2,792.5)	(66.8)	342.2
Cumulative effect of adopting new hedging standard	0.0				0.0	0.0
Beginning Balance at Mar. 31, 2018		3.2	2,889.3	(6.4)	(2,849.1)	(56.1)	351.0
Share-based compensation			1.8
Purchase of treasury stock				0.0
Net income	56.6				56.6
Change in accumulated other comprehensive income (loss)	(10.7)					(10.7)
Net income attributable to noncontrolling interests	15.7						15.7
Net distributions to noncontrolling interests							(24.5)
Ending Balance at Jun. 30, 2018	370.8	3.2	2,891.1	(6.4)	(2,792.5)	(66.8)	342.2
Cumulative effect of adopting new hedging standard	0.0				0.0	0.0
Beginning Balance at Dec. 31, 2018	429.5	3.2	2,894.9	(6.4)	(2,691.8)	(100.0)	329.6
Share-based compensation			6.1
Purchase of treasury stock				(0.8)
Net income	62.3				62.3
Change in accumulated other comprehensive income (loss)	(31.9)					(31.9)
Net income attributable to noncontrolling interests	25.7						25.7
Net distributions to noncontrolling interests							(15.3)
Ending Balance at Jun. 30, 2019	475.6	3.2	2,901.0	(7.2)	(2,629.5)	(131.9)	340.0
Cumulative effect of adopting new hedging standard	0.0
Beginning Balance at Mar. 31, 2019		3.2	2,899.2	(7.2)	(2,696.3)	(104.9)	335.8
Share-based compensation			1.8
Purchase of treasury stock				0.0
Net income	66.8				66.8
Change in accumulated other comprehensive income (loss)	(27.0)					(27.0)
Net income attributable to noncontrolling interests	13.1						13.1
Net distributions to noncontrolling interests							(8.9)
Ending Balance at Jun. 30, 2019	$ 475.6	$ 3.2	$ 2,901.0	$ (7.2)	$ (2,629.5)	$ (131.9)	$ 340.0