Quarterly report pursuant to Section 13 or 15(d)

Basis of Presentation and Significant Accounting Policies - Additional Information (Details)

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Basis of Presentation and Significant Accounting Policies - Additional Information (Details)
3 Months Ended 12 Months Ended
Mar. 31, 2018
USD ($)
Customer
Mar. 31, 2017
USD ($)
Customer
Dec. 31, 2017
Customer
Basis Of Presentation And Significant Accounting Policies [Line Items]      
Allocation of undistributed earnings to participating securities | $ $ 0 $ 0  
Contractual obligation | $ $ 0 $ 0  
Customer Concentration Risk [Member] | Trade Receivables [Member]      
Basis Of Presentation And Significant Accounting Policies [Line Items]      
Number of major partners | Customer 2   1
Customer Concentration Risk [Member] | Trade Receivables [Member] | Partner 1 [Member]      
Basis Of Presentation And Significant Accounting Policies [Line Items]      
Concentration risk, percentage (in hundredths) 50.00%   95.00%
Customer Concentration Risk [Member] | Revenues [Member]      
Basis Of Presentation And Significant Accounting Policies [Line Items]      
Number of major partners | Customer 2 2  
Customer Concentration Risk [Member] | Revenues [Member] | Partner 1 [Member]      
Basis Of Presentation And Significant Accounting Policies [Line Items]      
Concentration risk, percentage (in hundredths) 86.00% 58.00%  
Customer Concentration Risk [Member] | Revenues [Member] | Partner 2 [Member]      
Basis Of Presentation And Significant Accounting Policies [Line Items]      
Concentration risk, percentage (in hundredths) 13.00% 42.00%