| In millions, except per share items | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 | Jun-30-21 | Mar-31-21 | Dec-31-20 | Sep-30-20 |
| | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q |
| Current assets: | | | | | | | | |
| Cash and cash equivalents | | | | | | | | |
| Accounts receivable, net | 127.9 | 43.1 | 71.0 | 124.1 | 92.1 | 45.1 | 83.2 | 123.2 |
| Inventories | 131.5 | 143.8 | 104.0 | 100.1 | 93.9 | 99.9 | 79.5 | 93.7 |
| Inventories - truck chassis floor plan | 1.1 | 1.5 | 2.7 | 7.9 | 7.0 | 12.1 | 8.1 | 11.3 |
| Refundable income taxes paid | | 1.5 | 1.2 | 2.6 | 0.3 | | | 1.4 |
| Prepaid and other current assets | 4.0 | 4.8 | 4.5 | 5.6 | 4.5 | 5.2 | 5.3 | 4.7 |
| Total current assets | 270.5 | 202.9 | 220.4 | 247.6 | 213.1 | 197.9 | 217.2 | 248.7 |
| Property, plant, and equipment, net | 66.2 | 65.6 | 66.8 | 64.6 | 64.3 | 64.4 | 64.3 | 62.2 |
| Goodwill | 113.1 | 113.1 | 113.1 | 113.1 | 113.1 | 113.1 | 113.1 | 113.1 |
| Other intangible assets, net | 136.8 | 139.5 | 142.1 | 144.7 | 147.4 | 150.1 | 152.8 | 155.5 |
| Operating lease right-of-use assets | 16.2 | | | | | | | |
| Non-qualified benefit plan assets | 8.7 | 10.1 | 10.3 | 9.8 | 9.9 | 9.4 | 9.0 | |
| Other long-term assets | 1.9 | 1.9 | 1.2 | 1.2 | 1.3 | 1.3 | 1.3 | 9.3 |
| Total assets | 613.5 | 550.5 | 572.5 | 600.2 | 568.9 | 556.6 | 579.2 | 611.3 |
| |
| Current liabilities: | | | | | | | | |
| Accounts payable | 18.1 | 17.2 | 27.4 | 16.9 | 19.4 | 19.8 | 16.3 | 20.1 |
| Accrued expenses and other current liabilities | 32.1 | 27.2 | 36.1 | 32.7 | 33.3 | 27.4 | 30.8 | 28.7 |
| Floor plan obligations | 1.1 | 1.5 | 2.7 | 7.9 | 7.0 | 12.0 | 7.9 | 11.0 |
| Operating lease liability - current | 4.4 | 4.5 | 4.6 | 4.6 | 4.6 | 4.4 | 4.3 | 4.3 |
| Income taxes payable | 3.8 | | | | | 4.6 | 5.2 | |
| Short term borrowings | 58.0 | 12.0 | | 37.0 | | | | 12.0 |
| Current portion of long-term debt | 11.1 | 11.1 | 11.1 | 11.1 | 11.1 | 1.5 | 1.7 | 2.0 |
| Total current liabilities | 128.7 | 73.6 | 81.9 | 110.2 | 75.5 | 69.6 | 66.2 | 78.0 |
| Retiree benefits and deferred compensation | 15.8 | 17.2 | 17.2 | 17.2 | 17.3 | 16.9 | 15.8 | 6.7 |
| Deferred income taxes | 30.8 | 30.8 | 29.8 | 27.6 | 27.2 | 27.0 | 26.7 | 28.7 |
| Long-term debt, net | 200.7 | 203.4 | 206.1 | | | | 236.7 | |
| Operating lease liabilities | 13.3 | | | | | | | |
| Other long-term liabilities | 4.6 | 4.1 | 7.5 | 11.4 | 12.8 | 13.5 | 16.2 | 25.7 |
| |
| Stockholders’ equity: | | | | | | | | |
| Common Stock | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 |
| Additional paid-in capital | 162.6 | 162.5 | 163.6 | 163.8 | 163.8 | 159.7 | 157.8 | 157.7 |
| Retained earnings | 52.2 | 41.2 | 51.9 | 49.7 | 49.3 | 41.7 | 47.7 | 36.1 |
| Accumulated other comprehensive income (loss), net of tax | 4.6 | 3.2 | -1.1 | -3.5 | -4.1 | -5.0 | -5.5 | -6.1 |
| Total stockholders’ equity | 219.7 | 207.1 | 214.6 | 210.2 | 209.2 | 196.6 | 200.2 | 187.9 |
| Total liabilities and stockholders’ equity | 613.5 | 550.5 | 572.5 | 600.2 | 568.9 | 556.6 | 579.2 | 611.3 |