Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Jan. 01, 2018
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Deferred revenue contract liability	$ 23.0	$ 24.7
Contract acquisition cost amortization period	6 months
Deferred revenue recognized	$ 21.0
Capitalized contract cost amortization	$ 3.3
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
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
Prepaid Expenses
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer asset	$ 11.2
Other Assets
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Contract with customer asset	$ 32.2