Quarterly report pursuant to Section 13 or 15(d)

Accounts Receivable and Revenues from Contracts with Customers - Additional Information (Details)

v3.19.3
Accounts Receivable and Revenues from Contracts with Customers - Additional Information (Details) - Accounts Receivable
$ in Millions
9 Months Ended 12 Months Ended
Sep. 30, 2019
USD ($)
Customer
Sep. 30, 2018
USD ($)
Customer
Dec. 31, 2018
USD ($)
Credit Concentration Risk      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Concentration risk, percentage 60.00%   63.00%
Accounts receivable, major customers $ 32.9   $ 37.3
Customer Concentration Risk [Member]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Number of major customers | Customer 4 3  
Revenues, major customers $ 261.4 $ (254.5)  
Concentration risk, percentage 76.00% 81.00%  
Customer Concentration Risk [Member] | Major Customer 1      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Revenues, major customers $ (127.1)    
Concentration risk, percentage 37.00%    
Customer Concentration Risk [Member] | Major Customer 2      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Revenues, major customers $ (62.4)    
Concentration risk, percentage 18.00%    
Customer Concentration Risk [Member] | Major Customer 3      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Revenues, major customers $ (37.3)    
Concentration risk, percentage 11.00%    
Customer Concentration Risk [Member] | Major Customer Four [Domain]      
Accounts, Notes, Loans and Financing Receivable [Line Items]      
Revenues, major customers $ (34.6)    
Concentration risk, percentage 10.00%