Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Schedule of Carrying Value and Fair Value of Long-Term Debt (Details)

v3.19.1
Fair Value Measurements - Schedule of Carrying Value and Fair Value of Long-Term Debt (Details) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt, Carrying Value $ 634,005 $ 633,535
Credit Agreement    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt, Carrying Value 21,000 21,000
Credit Agreement | Fair Value, Inputs, Level 2    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt, Fair Value 21,000 21,000
Senior Second Lien Notes    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt, Carrying Value 613,005 612,535
Senior Second Lien Notes | Fair Value, Inputs, Level 2    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt, Fair Value $ 623,256 $ 546,875