THE SPIN-OFF, SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES AND OTHER - Major Customers (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Phillips 66 Company, Tesoro Refining Marketing Company Llc, Valero Marketing And Supply Company And Shell Trading (US) Company Combined
Major Customers
Concentration Risk, Percentage	67.00%
Major customers | Phillips 66 Company, Tesoro Refining & Marketing Company LLC and Valero Marketing & Supply Company Combined
Major Customers
Concentration Risk, Percentage		64.00%
Major customers | Conoco Phillips / Phillips 66 Company and Tesoro Refining & Marketing Company LLC Combined Member
Major Customers
Concentration Risk, Percentage			45.00%
Minimum | Major customers | Phillips 66 Company
Major Customers
Concentration Risk, Percentage	10.00%	10.00%
Minimum | Major customers | Tesoro Refining & Marketing Company LLC
Major Customers
Concentration Risk, Percentage	10.00%	10.00%	10.00%
Minimum | Major customers | Valero Marketing & Supply Company
Major Customers
Concentration Risk, Percentage	10.00%	10.00%
Minimum | Major customers | Shell Trading (US) Company
Major Customers
Concentration Risk, Percentage	10.00%
Minimum | Major customers | ConocoPhillips/Phillips 66 Company
Major Customers
Concentration Risk, Percentage			10.00%