Consolidated Statements of Changes in Shareholders' Equity (Deficit) Statement - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Noncontrolling Interest
Beginning balance (in shares) at Dec. 31, 2017		758.7				318.4
Beginning balance at Dec. 31, 2017	$ (714.7)	$ 189.7	$ 2,291.2	$ 2,320.3	$ (926.2)	$ (4,600.0)	$ 10.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(21.1)			(20.3)			(0.8)
Other comprehensive (loss) income	35.6				35.2		0.4
Dividends accrued - Series C convertible preferred stock	(6.0)			(6.0)
Exercise/ vesting/ expense of share-based compensation (in shares)		2.2				(0.1)
Exercise/ vesting/ expense of share-based compensation	3.6	$ 0.6	2.5	(0.4)		$ 0.9
Repurchase of common stock (in shares)						0.9
Repurchase of common stock	(2.7)					$ (2.7)
Purchases and sales of noncontrolling interests, net of dividends paid	(0.2)						(0.2)
Ending balance (in shares) at Mar. 31, 2018		760.9				319.2
Ending balance at Mar. 31, 2018	(746.6)	$ 190.3	2,293.7	2,252.5	(891.0)	$ (4,601.8)	9.7
Beginning balance (in shares) at Dec. 31, 2017		758.7				318.4
Beginning balance at Dec. 31, 2017	(714.7)	$ 189.7	2,291.2	2,320.3	(926.2)	$ (4,600.0)	10.3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	55.7
Other comprehensive (loss) income	(90.0)
Ending balance (in shares) at Sep. 30, 2018		761.7				319.4
Ending balance at Sep. 30, 2018	(803.0)	$ 190.3	2,299.1	2,318.3	(1,015.9)	$ (4,602.3)	7.5
Beginning balance (in shares) at Mar. 31, 2018		760.9				319.2
Beginning balance at Mar. 31, 2018	(746.6)	$ 190.3	2,293.7	2,252.5	(891.0)	$ (4,601.8)	9.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(37.0)			(36.1)			(0.9)
Other comprehensive (loss) income	(123.8)				(123.4)		(0.4)
Dividends accrued - Series C convertible preferred stock	(6.0)			(6.0)
Exercise/ vesting/ expense of share-based compensation (in shares)		0.8
Exercise/ vesting/ expense of share-based compensation	3.4		3.8	(0.4)
Repurchase of common stock (in shares)						0.2
Repurchase of common stock	(0.5)					$ (0.5)
Ending balance (in shares) at Jun. 30, 2018		761.7				319.4
Ending balance at Jun. 30, 2018	(910.5)	$ 190.3	2,297.5	2,210.0	(1,014.4)	$ (4,602.3)	8.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	113.8			114.5			(0.7)
Other comprehensive (loss) income	(1.7)				(1.5)		(0.2)
Dividends accrued - Series C convertible preferred stock	(6.2)			(6.2)
Exercise/ vesting/ expense of share-based compensation	1.6		1.6
Ending balance (in shares) at Sep. 30, 2018		761.7				319.4
Ending balance at Sep. 30, 2018	(803.0)	$ 190.3	2,299.1	2,318.3	(1,015.9)	$ (4,602.3)	7.5
Beginning balance (in shares) at Dec. 31, 2018		761.8				319.4
Beginning balance at Dec. 31, 2018	(896.8)	$ 190.3	2,303.6	2,234.3	(1,030.4)	$ (4,602.3)	7.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(33.5)			(32.7)			(0.8)
Other comprehensive (loss) income	(3.9)				(4.0)		0.1
Dividends accrued - Series C convertible preferred stock	(6.2)			(6.2)
Exercise/ vesting/ expense of share-based compensation (in shares)		1.3
Exercise/ vesting/ expense of share-based compensation	(1.2)	$ 0.3	(1.5)
Purchases and sales of noncontrolling interests, net of dividends paid	0.1						0.1
Ending balance (in shares) at Mar. 31, 2019		763.1				319.4
Ending balance at Mar. 31, 2019	(941.5)	$ 190.6	2,302.1	2,195.4	(1,034.4)	$ (4,602.3)	7.1
Beginning balance (in shares) at Dec. 31, 2018		761.8				319.4
Beginning balance at Dec. 31, 2018	(896.8)	$ 190.3	2,303.6	2,234.3	(1,030.4)	$ (4,602.3)	7.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	54.0
Other comprehensive (loss) income	(19.3)
Ending balance (in shares) at Sep. 30, 2019		763.4				319.9
Ending balance at Sep. 30, 2019	(875.2)	$ 190.4	2,310.5	2,270.0	(1,049.7)	$ (4,603.3)	6.9
Beginning balance (in shares) at Mar. 31, 2019		763.1				319.4
Beginning balance at Mar. 31, 2019	(941.5)	$ 190.6	2,302.1	2,195.4	(1,034.4)	$ (4,602.3)	7.1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(19.1)			(19.5)			0.4
Other comprehensive (loss) income	5.5				5.5		0.0
Dividends accrued - Series C convertible preferred stock	(6.4)			(6.4)
Exercise/ vesting/ expense of share-based compensation	5.4		5.4
Repurchase of common stock (in shares)		0.1				0.5
Repurchase of common stock	(1.0)	$ 0.1				$ (1.0)
Purchases and sales of noncontrolling interests, net of dividends paid	(0.3)						(0.3)
Ending balance (in shares) at Jun. 30, 2019		763.2				319.9
Ending balance at Jun. 30, 2019	(957.3)	$ 190.7	2,307.5	2,169.5	(1,028.9)	$ (4,603.3)	7.2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	106.6			106.9			(0.3)
Other comprehensive (loss) income	(20.8)				(20.8)
Dividends accrued - Series C convertible preferred stock	(6.4)			(6.4)
Exercise/ vesting/ expense of share-based compensation (in shares)		0.3
Exercise/ vesting/ expense of share-based compensation	3.3	$ 0.3	3.0
Repurchase of common stock	(0.6)	$ (0.6)
Ending balance (in shares) at Sep. 30, 2019		763.4				319.9
Ending balance at Sep. 30, 2019	$ (875.2)	$ 190.4	$ 2,310.5	$ 2,270.0	$ (1,049.7)	$ (4,603.3)	$ 6.9