| Summary of Segment Information | Segment results from operations for the years ended December 31, 2022, 2021 and 2020 were as follows: 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Year Ended December 31, 2022 |  |  |  |  |  | Expedited Freight |  | Intermodal |  |  |  | Corporate |  | Eliminations |  | Consolidated - Continuing Operations |  
| External revenues |  |  |  |  |  | $ | 1,553,705 |  |  | $ | 419,698 |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | 1,973,403 |  |  
| Intersegment revenues |  |  |  |  |  | 185 |  |  | 20 |  |  |  |  | — |  |  | (205) |  |  | — |  |  
| Depreciation |  |  |  |  |  | 24,656 |  |  | 6,641 |  |  |  |  | 101 |  |  | — |  |  | 31,398 |  |  
| Amortization |  |  |  |  |  | 7,236 |  |  | 8,752 |  |  |  |  | — |  |  | — |  |  | 15,988 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Income (loss) from continuing operations |  |  |  |  |  | 210,968 |  |  | 56,874 |  |  |  |  | (1,866) |  |  | — |  |  | 265,976 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Purchases of property and equipment |  |  |  |  |  | 39,459 |  |  | 1,270 |  |  |  |  | — |  |  | — |  |  | 40,729 |  | 
 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Year Ended December 31, 2021 |  |  |  |  |  | Expedited Freight |  | Intermodal |  |  |  | Corporate |  | Eliminations |  | Consolidated - Continuing Operations |  
| External revenues |  |  |  |  |  | $ | 1,373,313 |  |  | $ | 289,171 |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | 1,662,484 |  |  
| Intersegment revenues |  |  |  |  |  | 957 |  |  | 43 |  |  |  |  | — |  |  | (1,057) |  |  | (57) |  |  
| Depreciation |  |  |  |  |  | 21,623 |  |  | 3,538 |  |  |  |  | 63 |  |  | — |  |  | 25,224 |  |  
| Amortization |  |  |  |  |  | 7,219 |  |  | 7,109 |  |  |  |  | — |  |  | — |  |  | 14,328 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Income (loss) from continuing operations |  |  |  |  |  | 139,321 |  |  | 30,117 |  |  |  |  | (10,137) |  |  | — |  |  | 159,301 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Purchases of property and equipment |  |  |  |  |  | 36,364 |  |  | 2,745 |  |  |  |  | — |  |  | — |  |  | 39,109 |  | 
 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Year Ended December 31, 2020 |  |  |  |  |  | Expedited Freight |  | Intermodal |  |  |  | Corporate |  | Eliminations |  | Consolidated - Continuing Operations |  
| External revenues |  |  |  |  |  | $ | 1,070,106 |  |  | $ | 199,567 |  |  |  |  | $ | — |  |  | $ | — |  |  | $ | 1,269,673 |  |  
| Intersegment revenues |  |  |  |  |  | 2,195 |  |  | 36 |  |  |  |  | — |  |  | (2,331) |  |  | (100) |  |  
| Depreciation |  |  |  |  |  | 19,824 |  |  | 3,693 |  |  |  |  | 120 |  |  | — |  |  | 23,637 |  |  
| Amortization |  |  |  |  |  | 7,203 |  |  | 6,285 |  |  |  |  | — |  |  | — |  |  | 13,488 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Income (loss) from continuing operations |  |  |  |  |  | 71,266 |  |  | 16,391 |  |  |  |  | (13,733) |  |  | — |  |  | 73,924 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Purchases of property and equipment |  |  |  |  |  | 19,820 |  |  | 448 |  |  |  |  | — |  |  | — |  |  | 20,268 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| Total Assets |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
| As of December 31, 2022 |  |  |  |  |  | $ | 683,386 |  |  | $ | 322,001 |  |  |  |  | $ | 202,756 |  |  | $ | (67) |  |  | $ | 1,208,076 |  |  
| As of December 31, 2021 |  |  |  |  |  | 777,987 |  |  | 249,467 |  |  |  |  | 90,588 |  |  | (219) |  |  | 1,117,823 |  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 
 A reconciliation from the segment information to the consolidated balances for revenues is set forth below: 
 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  |  | Year Ended |  
|  |  | December 31, 2022
 |  | December 31, 2021
 |  | December 31, 2020
 |  
| Intersegment revenues - continuing operations |  | $ | — |  |  | $ | (57) |  |  | $ | (100) |  |  
| Intersegment revenues - discontinued operation |  | — |  |  | 57 |  |  | 100 |  |  
| Consolidated intersegment revenues |  | $ | — |  |  | $ | — |  |  | $ | — |  | Revenue from the individual services within the Expedited Freight segment for the years ended December 31, 2022, 2021 and 2020 were as follows: 
 
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|  |  | Year Ended |  
|  |  | December 31, 2022
 |  | December 31, 2021
 |  | December 31, 2020
 |  |  |  
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|  |  |  |  |  |  |  |  |  |  
| Expedited Freight revenues: |  |  |  |  |  |  |  |  |  
| Network |  | $ | 947,817 |  |  | $ | 805,015 |  |  | $ | 599,097 |  |  |  |  
| Truckload |  | 221,979 |  |  | 223,026 |  |  | 194,058 |  |  |  |  
| Final Mile |  | 293,769 |  |  | 275,201 |  |  | 224,475 |  |  |  |  
| Other |  | 90,325 |  |  | 71,028 |  |  | 54,671 |  |  |  |  
| Total |  | $ | 1,553,890 |  |  | $ | 1,374,270 |  |  | $ | 1,072,301 |  |  |  |  |