Quarterly report pursuant to Section 13 or 15(d)

Long-Tem Debt - Narrative (Details)

v3.19.1
Long-Tem Debt - Narrative (Details) - USD ($)
3 Months Ended 12 Months Ended
Jan. 11, 2018
Jan. 03, 2017
Mar. 31, 2019
Mar. 31, 2018
Dec. 31, 2017
Dec. 31, 2018
Debt Instrument [Line Items]            
Debt discount     $ 3,457,000     $ 3,300,000
Payment-in-kind interest     1,210,000 $ 1,193,000    
Less interest expense     9,363,000 6,929,000    
Amortization related to amortization of deferred finance costs and debt discounts     $ 400,000 300,000    
Syndicate of Lenders | Line of Credit            
Debt Instrument [Line Items]            
Interest rate during period     7.50%     7.53%
Quarterly principal payment   $ 800,000        
Syndicate of Lenders | Line of Credit | LIBOR            
Debt Instrument [Line Items]            
Applicable margin     5.00%   5.00%  
Syndicate of Lenders | Line of Credit | Term Loan | LIBOR            
Debt Instrument [Line Items]            
Applicable margin 5.00%          
Syndicate of Lenders | Line of Credit | Term Loan | Base Rate            
Debt Instrument [Line Items]            
Applicable margin 4.00%          
Syndicate of Lenders | Line of Credit | Revolving Credit Facility            
Debt Instrument [Line Items]            
Line of credit           $ 0
Unused commitment fee percentage 0.50%          
Syndicate of Lenders | Line of Credit | Revolving Credit Facility | LIBOR            
Debt Instrument [Line Items]            
Applicable margin 5.00%          
Syndicate of Lenders | Line of Credit | Revolving Credit Facility | Base Rate            
Debt Instrument [Line Items]            
Applicable margin 4.00%          
Goldman Sachs Specialty Lending Group | Line of Credit            
Debt Instrument [Line Items]            
Maximum borrowing capacity     $ 422,500,000      
Interest rate during period     10.50%     10.50%
Goldman Sachs Specialty Lending Group | Line of Credit | Term Loan            
Debt Instrument [Line Items]            
Maximum borrowing capacity     $ 397,500,000      
Remaining borrowing capacity     80,000,000.0      
Payment-in-kind interest     1,200,000 $ 1,200,000    
Goldman Sachs Specialty Lending Group | Line of Credit | Revolving Credit Facility            
Debt Instrument [Line Items]            
Maximum borrowing capacity     25,000,000.0      
Line of credit     $ 10,000,000.0      
Interest rate during period     9.50%      
Delayed Draw | Goldman Sachs Specialty Lending Group | Line of Credit | Term Loan            
Debt Instrument [Line Items]            
Maximum borrowing capacity           $ 70,000,000.0
Debt discount           $ 350,000
Unused commitment fee amount     $ 400,000