Segment Reporting (Details) $ in Thousands |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
|
Sep. 30, 2019
USD ($)
|
Sep. 30, 2018
USD ($)
|
Sep. 30, 2019
USD ($)
|
Sep. 30, 2018
USD ($)
|
Dec. 31, 2018
USD ($)
|
|
| Segment Reporting Information [Line Items] | |||||
| External revenues | $ 361,663 | $ 331,375 | $ 1,028,891 | $ 964,325 | |
| Depreciation | 7,534 | 8,079 | 23,864 | 24,623 | |
| Amortization | 2,994 | 2,216 | 8,172 | 6,723 | |
| Share-based compensation expense | 2,762 | 2,847 | 9,006 | 7,525 | |
| Interest expense | 761 | 472 | 1,916 | 1,327 | |
| Operating Income (Loss) | 30,689 | 29,879 | 85,973 | 86,984 | |
| Total assets | 980,633 | 743,141 | 980,633 | 743,141 | $ 760,215 |
| Capital expenditures | 10,504 | 16,738 | $ 27,102 | 34,344 | |
| Number of reportable segments | 4 | ||||
| Expedited LTL [Member] | |||||
| Segment Reporting Information [Line Items] | |||||
| External revenues | 207,423 | 186,544 | $ 588,766 | 546,066 | |
| Intersegment revenues | 2,638 | 1,963 | 5,570 | 5,276 | |
| Depreciation | 4,006 | 4,773 | 13,823 | 14,127 | |
| Amortization | 1,174 | 825 | 3,058 | 2,555 | |
| Share-based compensation expense | 1,899 | 1,961 | 6,193 | 5,595 | |
| Interest expense | 1 | ||||
| Operating Income (Loss) | 25,896 | 23,724 | 72,332 | 71,023 | |
| Total assets | 626,946 | 480,389 | 626,946 | 480,389 | |
| Capital expenditures | 8,658 | 15,253 | 22,330 | 31,960 | |
| Intermodal [Member] | |||||
| Segment Reporting Information [Line Items] | |||||
| External revenues | 58,317 | 50,496 | 162,936 | 148,058 | |
| Intersegment revenues | 29 | 49 | 64 | 217 | |
| Depreciation | 1,050 | 342 | 1,983 | 1,295 | |
| Amortization | 1,542 | 1,113 | 4,278 | 3,298 | |
| Share-based compensation expense | 340 | 262 | 1,313 | 776 | |
| Interest expense | 67 | 10 | 69 | 47 | |
| Operating Income (Loss) | 6,900 | 7,321 | 18,326 | 16,333 | |
| Total assets | 205,444 | 159,428 | 205,444 | 159,428 | |
| Capital expenditures | 207 | 276 | 422 | 482 | |
| Truckload Expedited [Member] | |||||
| Segment Reporting Information [Line Items] | |||||
| External revenues | 44,999 | 47,158 | 135,467 | 137,221 | |
| Intersegment revenues | 459 | 784 | 1,772 | 5,761 | |
| Depreciation | 1,182 | 1,522 | 4,225 | 4,765 | |
| Amortization | 21 | 21 | 64 | 98 | |
| Share-based compensation expense | (4) | 178 | 261 | 524 | |
| Interest expense | 2 | 2 | 6 | 5 | |
| Operating Income (Loss) | 606 | 1,673 | 2,137 | 3,348 | |
| Total assets | 75,622 | 70,841 | 75,622 | 70,841 | |
| Capital expenditures | 160 | 30 | 488 | 70 | |
| Pool Distribution [Member] | |||||
| Segment Reporting Information [Line Items] | |||||
| External revenues | 50,924 | 47,177 | 141,722 | 132,980 | |
| Intersegment revenues | 38 | 103 | 230 | 276 | |
| Depreciation | 1,296 | 1,442 | 3,834 | 4,436 | |
| Amortization | 257 | 257 | 772 | 772 | |
| Share-based compensation expense | 135 | 114 | 470 | 342 | |
| Operating Income (Loss) | 1,867 | 735 | 4,685 | 3,695 | |
| Total assets | 114,824 | 60,672 | 114,824 | 60,672 | |
| Capital expenditures | 1,479 | 1,179 | 3,862 | 1,832 | |
| Elimination [Member] | |||||
| Segment Reporting Information [Line Items] | |||||
| Intersegment revenues | (3,164) | (2,899) | (7,636) | (11,530) | |
| Depreciation | (1) | ||||
| Share-based compensation expense | 392 | 332 | 769 | 288 | |
| Interest expense | 692 | 460 | 1,841 | 1,274 | |
| Operating Income (Loss) | (4,580) | (3,574) | (11,507) | (7,415) | |
| Total assets | $ (42,203) | $ (28,189) | $ (42,203) | $ (28,189) | |