REPORTABLE SEGMENTS (Details) $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Segment results
Number of segments | segment	2
Fiscal Period Duration	371 days	364 days	364 days
Total Operating Revenue	$ 3,925.3	$ 2,383.3	$ 2,203.1
Operating Income	1,187.5	280.3	129.1
Interest expense, net	(22.6)	(27.4)	(22.5)
Other income (expense), net	6.4	6.1	1.2
Income before Income Taxes	1,171.3	259.0	107.8
Income taxes	(243.9)	(65.9)	(25.1)
Net Income	927.4	193.1	82.7
Deferred dry-docking amortization	24.3	25.1	34.3
Total Depreciation and Amortization	160.2	140.0	134.7
Assets	3,693.1	2,900.6
Income from SSAT	56.3	26.3	20.8
Ocean Transportation | SSAT
Segment results
Assets	1,583.1	1,543.8
Income from SSAT	56.3	26.3	20.8
Equity method investments	58.7	48.7
Operating segments
Segment results
Total Operating Revenue	3,925.3	2,383.3	2,203.1
Operating Income	1,187.5	280.3	129.1
Capital Expenditures	325.3	192.3	310.3
Depreciation and Amortization	135.9	114.9	100.4
Assets	3,693.1	2,900.6
Operating segments | Ocean Transportation
Segment results
Total Operating Revenue	3,132.8	1,853.9	1,666.6
Operating Income	1,137.7	244.8	90.8
Capital Expenditures	322.4	190.0	294.5
Depreciation and Amortization	128.6	107.4	93.6
Deferred dry-docking amortization	24.3	25.1	34.3
Assets	3,096.6	2,431.1
Operating segments | Logistics
Segment results
Total Operating Revenue	792.5	529.4	536.5
Operating Income	49.8	35.5	38.3
Capital Expenditures	2.9	2.3	15.8
Depreciation and Amortization	7.3	7.5	6.8
Assets	596.5	469.5
Intersegment Eliminations
Segment results
Total Operating Revenue	213.8	115.5	102.3
Intersegment Eliminations | Ocean Transportation
Segment results
Total Operating Revenue	81.0	59.1	52.8
Intersegment Eliminations | Logistics
Segment results
Total Operating Revenue	$ 132.8	$ 56.4	$ 49.5