Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Schedule of Estimated Fair Values of Financial Assets and Liabilities (Details)

v3.19.1
Fair Value Measurements - Schedule of Estimated Fair Values of Financial Assets and Liabilities (Details) - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Reported Value Measurement    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Cash, cash equivalents and restricted cash $ 66,095 $ 96,852
Investments, at cost, in 50% or less owned companies (included in other assets) 132 132
Long-term debt, including current portion 401,770 404,666
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 1    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Cash, cash equivalents and restricted cash 66,095 96,852
Estimate of Fair Value Measurement | Fair Value, Inputs, Level 2    
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]    
Long-term debt, including current portion $ 387,937 $ 388,949