Other Financial Information - Inventories, Net (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule Of Inventory [Line Items]
Production and service materials	$ 62.9	$ 71.2
Finished goods	33.1	26.6
Inventory	96.0	97.8
Prepaid expenses and other current assets
Schedule Of Inventory [Line Items]
Inventory	92.6	93.8
Other long-term assets
Schedule Of Inventory [Line Items]
Inventory	$ 3.4	$ 4.0