v3.19.3.a.u2

SEGMENT INFORMATION Narrative (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, Major Customer [Line Items]
Revenues	$ 399,694	$ 378,056	$ 372,445	$ 347,826	$ 374,137	$ 380,142	$ 389,256	$ 376,727	$ 1,498,021	$ 1,520,262	$ 1,444,772
Revenue Benchmark [Member] | Valero Energy Corporation [Member]
Revenue, Major Customer [Line Items]
Largest customer percentage of revenue									21.00%	20.00%	20.00%
Revenues									$ 307,200	$ 303,700	$ 294,500

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