Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue contract liability	$ 21.5	$ 21.5	$ 24.7
Contract acquisition cost amortization period	12 months	12 months
Deferred revenue recognized	$ 17.7	$ 39.1
Capitalized contract cost amortization	$ 2.7	$ 6.0
Minimum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Threshold period past due Company ceases billing and accruing late fees		30 days
Capitalized contract cost amortization period	5 years	5 years
Maximum
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Threshold period past due Company ceases billing and accruing late fees		40 days
Capitalized contract cost amortization period	10 years	10 years
Prepaid Expenses
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer asset	$ 11.4	$ 11.4
Other Assets
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer asset	$ 32.3	$ 32.3
Sales Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Consolidated revenues, net (percent)	100.00%	100.00%
Contracts with customers | Sales Revenue
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Consolidated revenues, net (percent)	90.00%	90.00%