Revenue from Contracts with Customers - Performance Obligation (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Revenue from Contract with Customer [Abstract]
Revenue recognized	$ 64.3	$ 43.9
Remaining performance obligation	$ 2,300.0
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, percentage	70.00%
Remaining performance obligation, expected timing	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligations, percentage	30.00%
Remaining performance obligation, expected timing