REPORTABLE SEGMENTS (Details) $ in Millions	3 Months Ended
	Mar. 31, 2025 USD ($) segment	Mar. 31, 2024 USD ($) segment
Segment results
Number of segments | segment	2	2
Total Operating Revenue	$ 782.0	$ 722.1
Operating costs:
Direct cargo expense	238.2	228.6
Vessel operating expense	147.4	153.0
Operating overhead	87.1	76.1
Direct operating costs	117.8	117.3
Depreciation and amortization	40.6	37.2
Total operating costs	631.1	612.2
Income from SSAT	(6.6)	(0.4)
General and administrative	75.4	73.4
Total Costs and Expenses	699.9	685.2
Operating Income	82.1	36.9
Interest income	9.4	8.8
Interest expense	(1.7)	(2.2)
Other income (expense), net	2.4	1.8
Income before Taxes	92.2	45.3
Income taxes	(19.9)	(9.2)
Net Income	72.3	36.1
Capital Expenditure	89.2	55.3
Capital expenditures included in accounts payable, accruals and other liabilities	7.6	16.0
SSAT
Operating costs:
Income from SSAT	(6.6)	(0.4)
Operating segments
Segment results
Total Operating Revenue	782.0	722.1
Intersegment Eliminations
Segment results
Total Operating Revenue	54.0	46.6
Ocean Transportation
Operating costs:
Direct cargo expense	238.2	228.6
Vessel operating expense	147.4	153.0
Operating overhead	87.1	76.1
Depreciation and amortization	37.2	34.4
Total operating costs	509.9	492.1
Income from SSAT	(6.6)	(0.4)
General and administrative	60.5	59.7
Total Costs and Expenses	563.8	551.4
Operating Income	73.6	27.6
Capital Expenditure	88.1	51.0
Dry-docking amortization	6.6	6.8
Ocean Transportation | Operating segments
Segment results
Total Operating Revenue	637.4	579.0
Ocean Transportation | Intersegment Eliminations
Segment results
Total Operating Revenue	21.4	19.7
Logistics
Operating costs:
Direct operating costs	117.8	117.3
Depreciation and amortization	3.4	2.8
Total operating costs	121.2	120.1
General and administrative	14.9	13.7
Total Costs and Expenses	136.1	133.8
Operating Income	8.5	9.3
Capital Expenditure	1.1	4.3
Logistics | Operating segments
Segment results
Total Operating Revenue	144.6	143.1
Logistics | Intersegment Eliminations
Segment results
Total Operating Revenue	$ 32.6	$ 26.9