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Revenue - Narratives (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Revenue from Contract with Customer [Abstract]        
Contract revenue recognized $ 28.8 $ 18.4 $ 67.7 $ 43.5
Remaining performance obligation $ 527.4   $ 527.4  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-07-01        
Disaggregation of Revenue        
Revenue, remaining performance obligation, Percentage 84.30%   84.30%  
Performance obligations expected to be satisfied, expected timing     1 year  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-07-01        
Disaggregation of Revenue        
Revenue, remaining performance obligation, Percentage 7.70%   7.70%  
Performance obligations expected to be satisfied, expected timing     1 year