NATURE OF OPERATIONS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Property and Equipment (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property and Equipment
Asset impairments		$ 1.0	$ 0.0	$ 0.0
Minimum | Buildings and improvements
Property and Equipment
Estimated useful lives		10 years
Minimum | Leasehold improvements
Property and Equipment
Estimated useful lives	[1]	5 years
Minimum | Revenue equipment - tractors, trailers and accessories
Property and Equipment
Estimated useful lives		5 years
Minimum | Revenue equipment leased and available for lease to owner operators
Property and Equipment
Estimated useful lives		5 years
Minimum | Vehicles
Property and Equipment
Estimated useful lives		5 years
Minimum | Furniture and fixtures
Property and Equipment
Estimated useful lives		5 years
Minimum | Office, computer equipment and capitalized software development
Property and Equipment
Estimated useful lives		3 years
Maximum | Buildings and improvements
Property and Equipment
Estimated useful lives		40 years
Maximum | Leasehold improvements
Property and Equipment
Estimated useful lives	[1]	20 years
Maximum | Revenue equipment - tractors, trailers and accessories
Property and Equipment
Estimated useful lives		15 years
Maximum | Revenue equipment leased and available for lease to owner operators
Property and Equipment
Estimated useful lives		15 years
Maximum | Vehicles
Property and Equipment
Estimated useful lives		7 years
Maximum | Furniture and fixtures
Property and Equipment
Estimated useful lives		7 years
Maximum | Office, computer equipment and capitalized software development
Property and Equipment
Estimated useful lives		5 years

[1] (1) or the term of the lease, whichever is shorter