Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2020
Percentage Of Income Tax Positions Likely To Be Realized	50.00%
Customer Relationships [Member] | Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	3 years
Customer Relationships [Member] | Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	20 years
Revenue Equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years	[1]
Revenue Equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	20 years	[1]
Shop and service equipment [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	2 years
Shop and service equipment [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	10 years
Land Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	5 years
Land Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	15 years
Building and Building Improvements [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	10 years
Building and Building Improvements [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	40 years
Furniture and Fixtures [Member] | Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Fixtures [Member] | Maximum [Member]
Property, Plant and Equipment, Useful Life	10 years

[1] *For finance leases involving revenue equipment, the depreciation period is equal to the term of the lease agreement.