Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements - Schedule of Instruments Not Carried at Fair Value (Details)

v3.10.0.1
Fair Value Measurements - Schedule of Instruments Not Carried at Fair Value (Details) - USD ($)
$ in Thousands
Jun. 30, 2018
Dec. 31, 2017
Long term debt, including current portion:    
Carrying value $ 1,731,235 $ 1,718,297
Fair value [1] $ 1,498,452 $ 1,645,616
[1] The fair value is based on market quotations from third party financial institutions and is classified as Level 2 in the hierarchy.