CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	Previously Reported	Preferred Stock	Preferred Stock Previously Reported	Common Stock	Common Stock Previously Reported	Additional Paid-in Capital	Additional Paid-in Capital Previously Reported	Treasury Stock	Treasury Stock Previously Reported	Accumulated Deficit	Accumulated Deficit Previously Reported	Accumulated Other Comprehensive (Loss) Income	Accumulated Other Comprehensive (Loss) Income Previously Reported	Total Stockholders' Equity	Total Stockholders' Equity Previously Reported	Non- controlling Interests	Non- controlling Interests Previously Reported
Balance (in shares)			2,000,000		284,221,168				0
Balance	$ 2,889.8		$ 0.0		$ 2.8		$ 3,981.3		$ 0.0		$ (573.5)		$ (674.5)		$ 2,736.1		$ 153.7
Balance (in shares)			2,000,000		284,221,168				0
Balance	2,889.8		$ 0.0		$ 2.8		3,981.3		$ 0.0		(573.5)		(674.5)		2,736.1		153.7
Balance (in shares) at Dec. 31, 2016			2,000,000		284,221,168				0
Balance at Dec. 31, 2016	2,889.8		$ 0.0		$ 2.8		3,981.3		$ 0.0		(573.5)		(674.5)		2,736.1		153.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(83.6)										(85.5)				(85.5)		1.9
Other comprehensive income, net of taxes	141.1												140.7		140.7		0.4
Exercise/ vesting of share based compensation (in shares)					93,300				6,618
Exercise/ vesting of share based compensation	(0.1)								$ (0.1)						(0.1)
Conversion of PDH Common Stock into common stock (in shares)					1,908,554
Conversion of PDH Common Stock into common stock	0.0						23.2								23.2		(23.2)
Issuance of common stock under ESPP (in shares)					67,984
Issuance of common stock under ESPP	0.6						0.6								0.6
Equity compensation expense	5.7						5.7								5.7
Changes in non-controlling interests	(1.2)						2.0								2.0		(3.2)
Balance (in shares) at Jun. 30, 2017			2,000,000		286,291,006				6,618
Balance at Jun. 30, 2017	2,952.3		$ 0.0		$ 2.8		4,012.8		$ (0.1)		(659.0)		(533.8)		2,822.7		129.6
Balance (in shares)			2,000,000		286,291,006				6,618
Balance	2,952.3		$ 0.0		$ 2.8		4,012.8		$ (0.1)		(659.0)		(533.8)		2,822.7		129.6
Balance (in shares)			2,000,000	2,000,000	287,405,939	287,405,939			6,618	6,618
Balance	2,860.0	$ 2,860.0	$ 0.0	$ 0.0	$ 2.9	$ 2.9	4,032.0	$ 4,032.0	$ (0.1)	$ (0.1)	(871.0)	$ (869.7)	(420.7)	$ (422.0)	2,743.1	$ 2,743.1	116.9	$ 116.9
Impact of ASU 2016-01 adoption | Accounting Standards Update 2016-01											(1.3)		1.3
Balance (in shares)			2,000,000	2,000,000	287,405,939	287,405,939			6,618	6,618
Balance	2,860.0	2,860.0	$ 0.0	$ 0.0	$ 2.9	$ 2.9	4,032.0	4,032.0	$ (0.1)	$ (0.1)	(871.0)	(869.7)	(420.7)	(422.0)	2,743.1	2,743.1	116.9	116.9
Balance (in shares) at Dec. 31, 2017			2,000,000	2,000,000	287,405,939	287,405,939			6,618	6,618
Balance at Dec. 31, 2017	2,860.0	$ 2,860.0	$ 0.0	$ 0.0	$ 2.9	$ 2.9	4,032.0	$ 4,032.0	$ (0.1)	$ (0.1)	(871.0)	$ (869.7)	(420.7)	$ (422.0)	2,743.1	$ 2,743.1	116.9	$ 116.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	49.8										49.3				49.3		0.5
Other comprehensive income, net of taxes	(309.9)												(276.6)		(276.6)		(33.3)
Exercise/ vesting of share based compensation (in shares)					44,549
Exercise/ vesting of share based compensation	0.0
Conversion of PDH Common Stock into common stock (in shares)					686,610
Conversion of PDH Common Stock into common stock	0.0						8.6								8.6		(8.6)
Issuance of common stock under ESPP (in shares)					70,807
Issuance of common stock under ESPP	0.6						0.6								0.6
Equity compensation expense	7.4						7.4								7.4
Changes in non-controlling interests	(3.5)																(3.5)
Balance (in shares) at Jun. 30, 2018			2,000,000		288,207,905				6,618
Balance at Jun. 30, 2018	2,604.4		$ 0.0		$ 2.9		4,048.6		$ (0.1)		(821.7)		(697.3)		2,532.4		72.0
Balance (in shares)			2,000,000		288,207,905				6,618
Balance	$ 2,604.4		$ 0.0		$ 2.9		$ 4,048.6		$ (0.1)		$ (821.7)		$ (697.3)		$ 2,532.4		$ 72.0