Segment Results: (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Segment results
Revenue	$ 416.6	$ 394.2	$ 811.3	$ 760.3
Operating income	36.5	32.5	55.2	38.6
Interest Expense	(3.6)	(1.9)	(7.3)	(3.9)
Income from Continuing Operations Before Income Taxes	32.9	30.6	47.9	34.7
Income Tax Expense	12.8	15.3	18.7	17.4
Income From Continuing Operations	20.1	15.3	29.2	17.3
Loss From Discontinued Operations (net of income taxes)	0	(7.5)	0	(6.1)
Net Income	20.1	7.8	29.2	11.2
Ocean Transportation
Segment results
Revenue	310.0	299.5	609.9	579.0
Operating income	34.3	31.2	52.8	37.0
Logistics
Segment results
Revenue	106.6	94.7	201.4	181.3
Operating income	$ 2.2	$ 1.3	$ 2.4	$ 1.6