v3.8.0.1

SEGMENT INFORMATION Narrative (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Revenue, Major Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue from largest customer | $ 450,535 | $ 440,566 | $ 435,488 | $ 487,430 | $ 471,757 | $ 441,418 | $ 437,804 | $ 405,703 | $ 1,814,019 | $ 1,756,682 | $ 2,084,040
Sales Revenue, Net [Member] | Valero Energy Corporation [Member] |  |  |  |  |  |  |  |  |  |  |
Revenue, Major Customer [Line Items] |  |  |  |  |  |  |  |  |  |  |
Largest customer percentage of revenue |  |  |  |  |  |  |  |  | 17.00% | 18.00% | 16.00%
Revenue from largest customer |  |  |  |  |  |  |  |  | $ 300,000 | $ 310,000 | $ 331,700

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