REPORTABLE SEGMENTS (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) segment	Jun. 30, 2016 USD ($)
Segment results
Number of segments \| segment			2
Operating Revenue	$ 512.5	$ 467.7	$ 986.9	$ 921.9
Operating Income	45.9	36.1	62.3	70.7
Interest expense, net	(6.3)	(6.5)	(12.6)	(11.4)
Income before Income Taxes	39.6	29.6	49.7	59.3
Income taxes	(15.6)	(11.6)	(18.7)	(23.2)
Net Income	24.0	18.0	31.0	36.1
Operating segments
Segment results
Operating Income	45.9	36.1	62.3	70.7
Intersegment Eliminations
Segment results
Operating Revenue	10.7	1.9	19.4	3.7
Ocean Transportation \| Operating segments
Segment results
Operating Revenue	392.7	370.9	762.7	737.0
Operating Income	39.0	33.9	53.5	66.9
Logistics \| Operating segments
Segment results
Operating Revenue	119.8	96.8	224.2	184.9
Operating Income	$ 6.9	$ 2.2	$ 8.8	$ 3.8

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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