Other Intangible Assets, net - Future Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization expense	$ 7.2	$ 14.6	$ 15.1
Expected future amortization of intangible assets
2018	5.3
2019	5.2
2020	5.2
2021	5.2
2022	5.1
2023 and Thereafter	28.1
Acquired Intangible Assets, Net	$ 54.1	$ 61.3