| Weighted Average Assumptions | 
 The weighted-average assumptions under the Monte Carlo simulation model were as follows:  
  
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February 12, 2021 | 
 
| Counterparty credit spread | 
1.2% | 
 
| Earnings before interest, taxes, depreciation and amortization discount rate | 
15.0% | 
 
| Asset volatility | 
55.0% | 
 
  
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| Summarized Held for Sale and Discontinued Operations Financial Information | 
 A summary of the results of operations classified as a discontinued operation, net of tax, in the Condensed Consolidated Statements of Comprehensive Income for the three months ended March 31, 2021 and 2020 is as follows:  
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|   | 
Three Months Ended | 
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March 31, 2021 | 
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March 31, 2020 | 
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| Operating revenue | 
$ | 
17,087  | 
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$ | 
36,952  | 
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| Operating expenses: | 
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| Purchased transportation | 
4,290  | 
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9,536  | 
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| Salaries, wages and employee benefits | 
9,674  | 
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17,113  | 
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| Operating leases | 
2,907  | 
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5,680  | 
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| Depreciation and amortization | 
—  | 
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1,295  | 
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| Insurance and claims | 
929  | 
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1,726  | 
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| Fuel expense | 
644  | 
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1,327  | 
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| Other operating expenses | 
2,087  | 
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4,345  | 
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| Total operating expenses | 
20,531  | 
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41,022  | 
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| Loss from discontinued operation | 
(3,444) | 
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(4,070) | 
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| Loss on sale of business  | 
(2,860) | 
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—  | 
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| Loss from discontinued operation before income taxes | 
(6,304) | 
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(4,070) | 
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| Income tax benefit | 
(771) | 
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(1,030) | 
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| Loss from discontinued operation, net of tax | 
$ | 
(5,533) | 
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$ | 
(3,040) | 
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