QUARTERLY INFORMATION (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Quarterly information by segments
Revenue	$ 410.9	$ 415.0	$ 416.6	$ 394.7	$ 398.3	$ 401.4	$ 394.2	$ 366.1	$ 1,637.2	$ 1,560.0	$ 1,462.6
Operating income	17.9	27.2	36.5	18.7	23.9	34.2	32.5	6.1	100.3	96.7	78.6
Interest expense	(3.5)	(3.6)	(3.6)	(3.7)	(3.8)	(4.0)	(1.9)	(2.0)	(14.4)	(11.7)	(7.7)
Income from Continuing Operations Before Income Taxes	14.4	23.6	32.9	15.0	20.1	30.2	30.6	4.1	85.9	85.0	70.9
Income tax expense	(7.1)	(6.4)	(12.8)	(5.9)	(4.4)	(11.2)	(15.3)	(2.1)	(32.2)	(33.0)	(25.1)
Income From Continuing Operations	7.3	17.2	20.1	9.1	15.7	19.0	15.3	2.0	53.7	52.0	45.8
Net Income (Loss) from Discontinued Operations Net of Income taxes					(0.1)	0.1	(7.5)	1.4	0	(6.1)	(11.6)
Net Income	7.3	17.2	20.1	9.1	15.6	19.1	7.8	3.4	53.7	45.9	34.2
Income From Continuing Operations, Earnings Per Share:
Basic (in dollars per share)	$ 0.17	$ 0.40	$ 0.47	$ 0.21	$ 0.37	$ 0.45	$ 0.36	$ 0.05	$ 1.26	$ 1.23	$ 1.10
Diluted (in dollars per share)	$ 0.17	$ 0.40	$ 0.47	$ 0.21	$ 0.37	$ 0.45	$ 0.36	$ 0.05	$ 1.25	$ 1.22	$ 1.09
Net Income, Earnings Per Share:
Basic (in dollars per share)	$ 0.17	$ 0.40	$ 0.47	$ 0.21	$ 0.37	$ 0.45	$ 0.18	$ 0.08	$ 1.26	$ 1.09	$ 0.82
Diluted (in dollars per share)	$ 0.17	$ 0.40	$ 0.47	$ 0.21	$ 0.36	$ 0.45	$ 0.18	$ 0.08	$ 1.25	$ 1.08	$ 0.81
Ocean transportation
Quarterly information by segments
Revenue	309.4	310.1	310.0	299.9	303.7	307.1	299.5	279.5	1,229.4	1,189.8	1,076.2
Operating income	16.0	25.5	34.3	18.5	26.7	32.9	31.2	5.8	94.3	96.6	73.7
Logistics services
Quarterly information by segments
Revenue	101.5	104.9	106.6	94.8	94.6	94.3	94.7	86.6	407.8	370.2	386.4
Operating income	$ 1.9	$ 1.7	$ 2.2	$ 0.2	$ (2.8)	$ 1.3	$ 1.3	$ 0.3	$ 6.0	$ 0.1	$ 4.9