INVESTMENT IN TERMINAL JOINT VENTURE (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Investments in affiliates
Investment in Terminal Joint Venture	$ 87.0	$ 93.2
Financial information for equity method investment
Equity in income of Terminal Joint Venture	36.8	28.2	$ 15.8
Distributions Received	$ 42.0	17.5
SSAT | Ocean Transportation
Investments in affiliates
Ownership interest accounted in the related party terminal joint venture (as a percent)	35.00%
Cost of services from transactions with unconsolidated affiliate	$ 213.4	181.3	177.8
Accounts payable and accrued liabilities	59.2	22.8
Financial information for equity method investment
Equity in income of Terminal Joint Venture	36.8	28.2	15.8
Current assets	310.4	181.0
Noncurrent assets	152.1	161.8
Total assets	462.5	342.8
Current liabilities	71.0	65.3
Noncurrent liabilities	156.2	23.8
Equity	235.3	253.7
Total Liabilities and Equity	462.5	342.8
Operating revenue	1,074.2	933.5	740.9
Operating costs and expenses	963.7	850.2	706.5
Operating Income	110.5	83.3	34.4
Net Income	$ 104.9	$ 80.9	$ 45.1