INVESTMENT IN TERMINAL JOINT VENTURE (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Investments in affiliates
Investment in terminal joint venture	$ 64.4	$ 57.6
Financial information for equity method investment
Company Share of Net Income (Loss)	6.6	(2.0)	3.2
SSAT | Ocean Transportation
Investments in affiliates
Ownership interest accounted in terminal joint venture (as a percent)	35.00%
Cost of services from transactions with unconsolidated affiliate	164.8	164.3	163.8
Dividends and distributions from the unconsolidated terminal venture	0	0	0
Accounts payable and accrued liabilities	17.5	15.3
Financial information for equity method investment
Current assets	80.7	73.5
Noncurrent assets	140.9	137.1
Total assets	221.6	210.6
Current liabilities	40.9	43.2
Noncurrent liabilities	7.1	15.7
Equity	173.6	151.7
Total Liabilities and Equity	221.6	210.6
Operating revenue	586.2	498.4	503.9
Operating costs and expenses	589.7	517.4	506.4
Operating loss	(3.5)	(19.0)	(2.5)
Net Income (Loss)	21.2	(5.7)	9.5
Company Share of Net Income (Loss)	$ 6.6	$ (2.0)	$ 3.2