Consolidated Statements of Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Accumulated Other Compre- hensive Income (Loss)	(Distribution in Excess of Accumulated Earnings) Earnings Surplus	Non-Controlling Interest	Redeem- able Non- Controlling Interest
Beginning balance (in shares) at Dec. 31, 2016		49.0
Beginning balance at Dec. 31, 2016	$ 1,213.2	$ 1,157.3	$ (43.2)	$ 95.2	$ 3.9
Total Equity
Net income (loss)	229.3			228.3	1.0
Other comprehensive income (loss), net of tax	0.9		0.9
Dividend on common stock	(793.3)			(793.3)
Distributions to noncontrolling interest	(0.2)				(0.2)	$ (0.3)
Adjustments to redemption value of redeemable noncontrolling interest	3.7			3.7
Share-based compensation	4.4	$ 4.4
Shares issued or repurchased, net (in shares)		0.3
Shares issued or repurchased, net	(6.9)			(6.9)
Ending balance at Dec. 31, 2017	651.1	$ 1,161.7	(42.3)	(473.0)	4.7
Ending balance (in shares) at Dec. 31, 2017		49.3
Redeemable Non-Controlling Interest, beginning balance at Dec. 31, 2016						10.8
Redeemable Non-Controlling Interest
Net income (loss)	(1.8)					1.2
Distributions to noncontrolling interest	(0.2)				(0.2)	(0.3)
Adjustments to redemption value of redeemable noncontrolling interest						(3.7)
Redeemable Non-Controlling Interest, ending balance at Dec. 31, 2017						8.0
Total Equity
Net income (loss)	(70.5)			(72.0)	1.5
Other comprehensive income (loss), net of tax	(0.5)		(0.5)
Stock dividend ($11.65 per share) (in shares)		22.6
Stock dividend ($11.65 per share)	626.4	$ 626.4
Distributions to noncontrolling interest	(0.5)				(0.5)	(0.2)
Adjustments to redemption value of redeemable noncontrolling interest	0.6	0.6
Share-based compensation	4.7	$ 4.7
Shares issued or repurchased, net (in shares)		0.1
Shares issued or repurchased, net	(1.6)			(1.6)
Ending balance at Dec. 31, 2018	1,208.3	$ 1,793.4	(51.9)	(538.9)	5.7
Ending balance (in shares) at Dec. 31, 2018		72.0
Redeemable Non-Controlling Interest
Net income (loss)	0.0					0.7
Distributions to noncontrolling interest	(0.5)				(0.5)	(0.2)
Adjustments to redemption value of redeemable noncontrolling interest						(0.6)
Redeemable Non-Controlling Interest, ending balance at Dec. 31, 2018	7.9					7.9
Total Equity
Net income (loss)	(38.5)			(36.4)	(2.1)
Other comprehensive income (loss), net of tax	3.1		3.1
Dividend on common stock	(50.0)			(50.0)
Distributions to noncontrolling interest						(0.3)
Adjustments to redemption value of redeemable noncontrolling interest	1.4	$ 1.4
Share-based compensation	5.4	$ 5.4
Shares issued or repurchased, net (in shares)		0.3
Shares issued or repurchased, net	(1.0)	$ (0.1)		(0.9)
Ending balance at Dec. 31, 2019	1,128.7	$ 1,800.1	$ (48.8)	$ (626.2)	$ 3.6
Ending balance (in shares) at Dec. 31, 2019		72.3
Redeemable Non-Controlling Interest
Net income (loss)	0.0					0.1
Distributions to noncontrolling interest						(0.3)
Adjustments to redemption value of redeemable noncontrolling interest						(1.4)
Redeemable Non-Controlling Interest, ending balance at Dec. 31, 2019	$ 6.3					$ 6.3