REPORTABLE SEGMENTS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) segment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Segment results
Number of segments | segment	2
Fiscal Period Duration	364 days	364 days	364 days
Total Operating Revenue	$ 3,094.6	$ 4,343.0	$ 3,925.3
Total Operating Income	342.8	1,353.6	1,187.5
Interest income	36.0	8.2
Interest expense	(12.2)	(18.0)	(22.6)
Other income (expense), net	6.4	8.5	6.4
Income before Taxes	373.0	1,352.3	1,171.3
Income taxes	(75.9)	(288.4)	(243.9)
Net Income	297.1	1,063.9	927.4
Deferred dry-docking amortization	25.3	24.9	24.3
Total Depreciation and Amortization	169.7	166.2	160.2
Total Assets	4,294.6	4,330.0
Income from SSAT	2.2	83.1	56.3
Operating segments
Segment results
Total Operating Revenue	3,094.6	4,343.0	3,925.3
Total Operating Income	342.8	1,353.6	1,187.5
Total Capital Expenditures	248.4	209.3	325.3
Depreciation and Amortization	144.4	141.3	135.9
Total Assets	4,294.6	4,330.0
Intersegment Eliminations
Segment results
Total Operating Revenue	208.7	270.9	213.8
Ocean Transportation | SSAT
Segment results
Income from SSAT	2.2	83.1	56.3
Equity method investments	85.5	81.2
Ocean Transportation | Operating segments
Segment results
Total Operating Revenue	2,477.0	3,544.6	3,132.8
Total Operating Income	294.8	1,281.2	1,137.7
Total Capital Expenditures	240.2	190.9	322.4
Depreciation and Amortization	132.8	133.2	128.6
Deferred dry-docking amortization	25.3	24.9	24.3
Total Assets	3,645.3	3,705.2
Ocean Transportation | Intersegment Eliminations
Segment results
Total Operating Revenue	76.5	93.6	81.0
Logistics | Operating segments
Segment results
Total Operating Revenue	617.6	798.4	792.5
Total Operating Income	48.0	72.4	49.8
Total Capital Expenditures	8.2	18.4	2.9
Depreciation and Amortization	11.6	8.1	7.3
Total Assets	649.3	624.8
Logistics | Intersegment Eliminations
Segment results
Total Operating Revenue	$ 132.2	$ 177.3	$ 132.8