Revenue - Performance Obligations (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Transferred at Point in Time
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues, percent	90.50%	91.30%	92.30%	92.80%
Transferred over Time
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenues, percent	9.50%	8.70%	7.70%	7.20%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation	$ 69.1		$ 69.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01 | Minimum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation period	12 months		12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01 | Maximum
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation period	18 months		18 months