SIGNIFICANT ACCOUNTING POLICIES - RECOGNITION OF REVENUES AND EXPENSES (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Total	$ 524.1	$ 557.9		$ 1,038.0	$ 1,090.3
Ocean Transportation
Ocean Transportation services	402.6	406.6
Terminal and other related services	4.6	4.8
Fuel sales	2.1	2.6
Vessel management services and related costs	1.5	1.4
Percentage of ocean transportation revenues and fuel sales denominated in foreign currency				3.00%	3.00%
Total	410.8	415.4
Logistics
Transportation Brokerage and Freight Forwarding Services	101.9	131.7
Warehouse and distribution services	8.2	8.3
Supply chain management and other services	3.2	2.5
Total	113.3	142.5
Percentage of transportation brokerage and freight forwarding services revenue denominated in foreign currency				3.00%	3.00%
Ocean Transportation
Ocean Transportation services				$ 793.7	$ 794.5
Terminal and other related services				10.4	11.5
Fuel sales				4.7	4.6
Vessel management services and related costs				2.9	2.7
Total	410.8	415.4		811.7	813.3
Logistics
Transportation Brokerage and Freight Forwarding Services				204.0	255.0
Warehouse and distribution services				16.4	16.7
Supply chain management and other services				5.9	5.3
Total	$ 113.3	$ 142.5		$ 226.3	277.0
Reclassify Transportation Brokerage and Freight Forwarding Services
Transportation Brokerage and Freight Forwarding Services			$ (3.0)		(6.1)
Warehouse and distribution services			$ 3.1		$ 6.1