SIGNIFICANT ACCOUNTING POLICIES - RECOGNITION OF REVENUES AND EXPENSES (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total	$ 540.7	$ 572.1	$ 557.9	$ 532.4	$ 564.9	$ 589.4	$ 557.1	$ 511.4	$ 2,203.1	$ 2,222.8	$ 2,046.9
Ocean Transportation
Total	416.1	437.2	415.4	397.9	418.1	437.3	406.6	379.3
Logistics
Total	$ 124.6	$ 134.9	$ 142.5	$ 134.5	$ 146.8	$ 152.1	$ 150.5	$ 132.1
Ocean Transportation
Ocean Transportation services									1,625.8	1,599.3	1,531.8
Terminal and other related services									24.8	23.0	23.5
Fuel sales									10.1	12.2	9.9
Vessel management and related services									$ 5.9	6.8	6.6
Percentage of ocean transportation revenues and fuel sales denominated in foreign currency									3.00%
Total									$ 1,666.6	1,641.3	1,571.8
Logistics
Transportation Brokerage and Freight Forwarding Services									504.8	549.1	445.1
Warehouse and distribution services									20.6	19.1	17.5
Supply chain management and other services									11.1	13.3	12.5
Total									$ 536.5	$ 581.5	$ 475.1
Percentage of transportation brokerage and freight forwarding services revenue denominated in foreign currency									3.00%