Condensed Consolidated Statements of Income and Comprehensive Income (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Operating Revenue:
Ocean transportation	$ 310.1	$ 307.1	$ 920.0	$ 886.1
Logistics	104.9	94.3	306.3	275.6
Total operating revenue	415.0	401.4	1,226.3	1,161.7
Costs and Expenses:
Operating costs	353.6	337.0	1,041.3	996.0
Equity in loss (income) of terminal joint venture	2.4	(0.7)	3.0	(3.1)
Selling, general and administrative	31.8	30.6	99.6	87.4
Separation costs		0.3		8.6
Operating costs and expenses	387.8	367.2	1,143.9	1,088.9
Operating Income	27.2	34.2	82.4	72.8
Interest expense	(3.6)	(4.0)	(10.9)	(7.9)
Income from Continuing Operations Before Income Taxes	23.6	30.2	71.5	64.9
Income tax expense	(6.4)	(11.2)	(25.1)	(28.6)
Income From Continuing Operations	17.2	19.0	46.4	36.3
Income (Loss) From Discontinued Operations (net of income taxes)		0.1		(6.0)
Net Income	17.2	19.1	46.4	30.3
Other Comprehensive Income, Net of Tax:
Net Income	17.2	19.1	46.4	30.3
Defined benefit pension plans:
Net loss and prior service cost			(0.8)	(1.1)
Less: amortization of prior service credit included in net periodic pension cost	(0.3)	(0.5)	(1.0)	(1.0)
Less: amortization of net loss included in net periodic pension cost	1.2	1.3	3.5	3.5
Foreign currency translation adjustment	0.1		(0.1)
Other Comprehensive Income	1.0	0.8	1.6	1.4
Comprehensive Income	$ 18.2	$ 19.9	$ 48.0	$ 31.7
Basic Earnings Per Share:
Continuing operations (in dollars per share)	$ 0.40	$ 0.45	$ 1.09	$ 0.86
Discontinued operations (in dollars per share)				$ (0.14)
Net income (in dollars per share)	$ 0.40	$ 0.45	$ 1.09	$ 0.72
Diluted Earnings Per Share:
Continuing operations (in dollars per share)	$ 0.40	$ 0.45	$ 1.08	$ 0.85
Discontinued operations (in dollars per share)				$ (0.14)
Net income (in dollars per share)	$ 0.40	$ 0.45	$ 1.08	$ 0.71
Weighted Average Number of Shares Outstanding:
Basic (in shares)	42.8	42.5	42.7	42.2
Diluted (in shares)	43.3	42.8	43.1	42.6
Cash Dividends Per Share (in dollars per share)	$ 0.16	$ 0.15	$ 0.46	$ 0.78