Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Basis of Presentation and Significant Accounting Policies - Additional Information (Details)
3 Months Ended 12 Months Ended
Mar. 31, 2019
USD ($)
Customer
Mar. 31, 2018
USD ($)
Customer
Dec. 31, 2018
USD ($)
Customer
Jan. 01, 2019
USD ($)
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Operating lease right-of-use assets $ 6,906,000      
Operating lease liabilities 8,648,000      
Dividends declared 0 $ 0    
Customer Concentration Risk [Member]        
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Cash equivalents $ 0   $ 0  
Customer Concentration Risk [Member] | Trade Receivables [Member]        
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Number of major partners | Customer 1   2  
Customer Concentration Risk [Member] | Trade Receivables [Member] | Partner 1 [Member]        
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Concentration risk, percentage (in hundredths)     67.00%  
Customer Concentration Risk [Member] | Trade Receivables [Member] | Partner 2 [Member]        
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Concentration risk, percentage (in hundredths)     28.00%  
Customer Concentration Risk [Member] | Revenues [Member]        
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Number of major partners | Customer 1 2    
Customer Concentration Risk [Member] | Revenues [Member] | Partner 1 [Member]        
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Concentration risk, percentage (in hundredths) 99.00% 86.00%    
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%    
ASC 842 [Member]        
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Operating lease right-of-use assets       $ 7,400,000
Operating lease liabilities       $ 9,200,000
ASC 842 [Member] | Lease-related Costs [Member]        
Basis Of Presentation And Significant Accounting Policies [Line Items]        
Lease-related restructuring liabilities, carrying amount     $ 1,700,000