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Revenue Recognition (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Revenue from External Customer [Line Items]      
Contract assets $ 0.0   $ 0.0
Deferred Revenue, revenue recognized 21.6    
Capitalized contract cost, costs to fulfill a contract 0.2   $ 0.1
Capitalized contract cost, amortization $ 0.1 $ 0.0  
Contract operations revenue      
Revenue from External Customer [Line Items]      
Services generally billed in number of months in advance of service commencement 1 month    
Expected timing of satisfaction of service, period 30 days    
Contract operations revenue | Minimum      
Revenue from External Customer [Line Items]      
Typical initial contract terms 6 months    
Contract operations revenue | Maximum      
Revenue from External Customer [Line Items]      
Typical initial contract terms 5 years    
Retail parts and services revenue      
Revenue from External Customer [Line Items]      
Expected timing of satisfaction of service, period 30 days