Revenue Recognition - Contract Liabilities (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2018	Jan. 01, 2018
Contract with Customer, Asset
Contract Assets	$ 1.0	$ 1.8	$ 1.4	$ 1.7	$ 1.0	$ 0.6
Change in period	(0.8)	0.4	(0.3)	1.1
Contract Liabilities
Contract Liabilities - Current	11.3	11.2	11.6	11.5	11.3	11.3
Increase (decrease) - Current Liabilities	0.1	(0.4)	0.1	0.2
Current Liabilities - Noncurrent	$ 2.7	$ 2.7	2.7	2.4	$ 2.7	$ 2.1
Increase (decrease) - Noncurrent Liabilities			$ 0.3	$ 0.3
Revenue practical expedient, financial component					true
Revenue recognized, contract liability					$ 11.3
Impairment loss related to Contract Assets					$ 0.0
Revenue practical expedient, incremental cost of obtaining contract					true