SIGNIFICANT ACCOUNTING POLICIES - RECOGNITION OF REVENUES AND EXPENSES (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total	$ 700.1	$ 645.2	$ 524.1	$ 513.9	$ 540.7	$ 572.1	$ 557.9	$ 532.4	$ 2,383.3	$ 2,203.1	$ 2,222.8
Ocean Transportation
Total	543.9	498.3	410.8	400.9	416.1	437.2	415.4	397.9
Logistics
Total	$ 156.2	$ 146.9	$ 113.3	$ 113.0	$ 124.6	$ 134.9	$ 142.5	$ 134.5
Ocean Transportation
Ocean Transportation services									1,821.7	1,625.8	1,599.3
Terminal and other related services									19.1	24.8	23.0
Fuel sales									7.3	10.1	12.2
Vessel management and related services									$ 5.8	$ 5.9	$ 6.8
Percentage of ocean transportation revenues and fuel sales denominated in foreign currency									3.00%	3.00%	3.00%
Total									$ 1,853.9	$ 1,666.6	$ 1,641.3
Logistics
Transportation Brokerage and Freight Forwarding Services									477.0	489.0	532.5
Warehouse and distribution services									36.2	34.1	33.8
Supply chain management and other services									16.2	13.4	15.2
Total									$ 529.4	$ 536.5	$ 581.5
Percentage of transportation brokerage and freight forwarding services revenue denominated in foreign currency									3.00%	3.00%	3.00%
Reclassify Transportation Brokerage and Freight Forwarding Services | Logistics
Transportation Brokerage and Freight Forwarding Services										$ (15.8)	$ (16.6)
Warehouse and distribution services										$ 15.8	$ 16.6