Goodwill and Other Intangible Assets - Goodwill Rollforward (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015
Acquired Finite-Lived Intangible Assets [Line Items]
Liabilities	$ 299.9		$ 299.9		$ 2,804.2
Goodwill [Roll Forward]
Goodwill, beginning balance	25.9	$ 18.3	25.9	$ 18.6
Intangible assets, net (including Goodwill), beginning balance	40.3	41.6	45.2	45.5
Add: Amounts held for sale at beginning of the period					0.0	$ 0.4
Acquisition of businesses	0.0	1.1	0.0
Wobi write off				(0.3)
Wobi write off				(2.8)
Acquisitions of goodwill		7.6		7.6
Amortization, including foreign currency translation	(2.5)	(2.6)	(7.4)	(8.0)
Goodwill, ending balance	25.9	25.9	25.9	25.9
Intangible assets, net (including Goodwill), ending balance	37.8	47.7	37.8	47.7
Assets	3,637.1		3,637.1		6,520.2
Other Intangible Assets
Goodwill [Roll Forward]
Other intangible assets, beginning balance	14.4	23.3	19.3	26.9
Add: Amounts held for sale at beginning of the period					$ 0.0	$ 0.4
Acquisition of businesses				5.0
Wobi write off				(2.5)
Amortization, including foreign currency translation	(2.5)	(2.6)	(7.4)	(8.0)
Other intangible assets, ending balance	$ 11.9	21.8	$ 11.9	21.8
Intangible Asset and Goodwill
Goodwill [Roll Forward]
Acquisition of businesses		$ 8.7		$ 12.6