The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Amount of investment in marketable security, classified as noncurrent.

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Cash received on stock transaction after deduction of issuance costs.

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Percentage of subsidiary's or equity investee's stock owned by parent company after stock transaction.

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Equity and Other Investments (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Jan. 02, 2013	Feb. 29, 2020	Dec. 31, 2022	Dec. 31, 2021	Apr. 15, 2021	Dec. 31, 2020
Equity and Other Investments:
Investment in equity securities			$ 600	$ 12,700		$ 5,000
Number of shares held						353,604
Unrealized loss (gain) on investment			$ (12,096)	7,677
TuSimple
Equity and Other Investments:
Share price					$ 40.00
DriverTech
Equity and Other Investments:
Ownership interest, as a percent			20.73%
Investment carrying value				$ 0		$ 0
DriverTech \| Management of US Xpress
Equity and Other Investments:
Ownership interest, as a percent			12.00%
DriverTech \| Unspecified investors
Equity and Other Investments:
Ownership interest, as a percent			67.27%
Parker Global Enterprises, Inc.
Equity and Other Investments:
Loss on sale of investments		$ (2,000)
Stock ownership received, as a percent	45.00%
Value of stock received	$ 10,400
Unrealized loss (gain) on investment			$ 1,300