Fair Value Measurement - Recurring and Nonrecurring Measurements (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended			12 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024		Sep. 30, 2023	Dec. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[1]	$ 40,000		$ 40,000			$ 40,859
Asset Impairment Charges		(1,008)	$ 0	(10,867)		$ 0
Gain (Loss) on Disposition of Property Plant Equipment				21,839		46,628
Equipment [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment		9,200	11,400	21,800		46,600
U.S. Xpress | Class A
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[1]	134,107		134,107			134,107
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		0		0			0
Business Combination, Contingent Consideration, Liability	[2]	40,000		40,000			40,859
Contingent Consideration Gain (Loss)		900	$ 900	859	[2]	$ 3,400	3,359	[2]
Total pension plan assets		35,907		35,907			35,423
Fair Value, Recurring [Member] | U.S. Xpress | Class A
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[2]	134,107		134,107			134,107
Contingent Consideration Gain (Loss)	[2]			0			0
Fair Value, Recurring [Member] | Fixed income funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total pension plan assets		34,528		34,528			34,536
Fair Value, Recurring [Member] | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total pension plan assets		1,379		1,379			887
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[2]	0		0			0
Total pension plan assets		35,907		35,907			35,423
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | U.S. Xpress | Class A
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[2]	0		0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Fixed income funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total pension plan assets		34,528		34,528			34,536
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total pension plan assets		1,379		1,379			887
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[2]	0		0			0
Total pension plan assets		0		0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | U.S. Xpress | Class A
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[2]	0		0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Fixed income funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total pension plan assets		0		0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total pension plan assets		0		0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[2]	40,000		40,000			40,859
Total pension plan assets		0		0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | U.S. Xpress | Class A
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability	[2]	134,107		134,107			134,107
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Fixed income funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total pension plan assets		0		0			0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Cash and cash equivalents
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total pension plan assets		0		0			0
Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial and Nonfinancial Liabilities, Fair Value Disclosure		0		0			0
Fair Value, Nonrecurring [Member] | Software and Software Development Costs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[3]						0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member] | Software and Software Development Costs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[3]						0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member] | Software and Software Development Costs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[3]						0
Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member] | Software and Software Development Costs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[3]						0
Building and Building Improvements | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[4]	0		0			0
Asset Impairment Charges	[4]			(288)			(187)
Building and Building Improvements | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[4]	0		0			0
Building and Building Improvements | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[4]	0		0			0
Building and Building Improvements | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[4]	0		0			0
Property Subject to Operating Lease | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[5]	0		0
Asset Impairment Charges	[5]			(5,300)
Property Subject to Operating Lease | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[5]	0		0
Property Subject to Operating Lease | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[5]	0		0
Property Subject to Operating Lease | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[5]	0		0
Equipment [Member] | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[6]	0		0			0
Total Losses, nonrecurring assets	[6]			(5,279)			(469)
Equipment [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[6]	0		0			0
Equipment [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[6]	0		0			0
Equipment [Member] | Fair Value, Nonrecurring [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure	[6]	$ 0		$ 0			0
Software and Software Development Costs | Fair Value, Nonrecurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset Impairment Charges	[3]						$ (1,580)

[1] The contingent consideration is primarily related to the U.S. Xpress Acquisition.

[2] Contingent consideration is associated with the U.S. Xpress Acquisition and certain other investments. The Company recognized a gain of $0.9 million during the quarter and year-to-date periods ended September 30, 2024. The Company recognized a gain of $0.9 million during the quarter ended September 30, 2023 and a gain of $3.4 million during the year-to-date period ended September 30, 2023. 2As of September 30, 2024, the call option has expired and the mandatorily redeemable contingent consideration is now in the put option period.

[3] Reflects the non-cash impairment of software (within the All Other Segments).

[4] Reflects the non-cash impairment of building improvements (within the Truckload segment and the All Other Segments).

[5] Reflects the non-cash impairment related to the market value of a facility lease (within the Truckload Segment).

[6] Reflects the non-cash impairment of certain revenue equipment held for sale and other equipment (within the Truckload segment and the All Other Segments).