SIGNIFICANT ACCOUNTING POLICIES - INVESTMENT IN TERMINAL JOINT VENTURE (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Investments in affiliates
Investment in Terminal Joint Venture	$ 94.4		$ 94.4		$ 93.2
Financial information for equity method investment
Company Share of Net Income	9.1	$ 6.9	19.6	$ 11.8
SSAT
Financial information for equity method investment
Operating revenue	266.1	214.1	517.0	410.8
Operating costs and expenses	(240.4)	(194.0)	(460.1)	(378.0)
Operating Income	25.7	20.1	56.9	32.8
Net Income	$ 24.3	$ 19.5	$ 55.0	$ 33.8

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The amount of the cost of sales reported by an equity method investment of the entity.

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