Discontinued Operations Additional Information (Details) - USD ($) $ in Millions		3 Months Ended								9 Months Ended		12 Months Ended
	Aug. 18, 2016	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Proceeds from Divestiture of Businesses										$ 2,759.4	$ (5.2)	$ 2,759.4	$ (5.2)	$ (3.0)	$ (3.0)
(Gain) loss from sale / impairment of discontinued operations, net of tax		$ 17.8	$ 1.7	$ (200.6)	$ 0.0	$ 0.0	$ (0.6)	$ 0.0	$ 0.0			(181.1)	(0.6)	6.7
Gain (loss) from sale / impairment of discontinued operations, net of tax		$ (3.5)	$ 0.0	$ 5.2	$ (7.1)	$ (21.4)	$ (22.9)	$ (10.1)	$ (15.6)			(5.4)	(70.0)	466.8
Discontinued Operation, Tax (Expense) Benefit from Provision for (Gain) Loss on Disposal												2.4	$ 0.0	0.0
Discontinued Operations, Disposed of by Sale [Member]
Business Acquisition [Line Items]
Proceeds from Divestiture of Businesses	$ 3,150.0													$ 59.0
Discontinued Operations [Member]
Business Acquisition [Line Items]
Business Exit Costs												$ 56.4