| In millions, except per share items | Sep-30-20 | Jun-30-20 | Mar-31-20 | Dec-31-19 | Sep-30-19 | Jun-30-19 | Mar-31-19 | Dec-31-18 |
| | 10-Q | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K |
| Revenue | 49.3 | 33.8 | 67.4 | 79.8 | 77.4 | 89.6 | 86.1 | 89.3 |
| Revenue growth | -36.3% | -62.3% | -21.8% | -10.6% | 2.7% | -8.6% | -8.9% | 13.4% |
| Other Income | 0.1 | 7.5 | 2.7 | 2.4 | 1.1 | 1.0 | 1.3 | 0.9 |
| Total Revenue and Other Income | 49.3 | 33.8 | 67.4 | 79.8 | 77.4 | 89.6 | 86.1 | 89.3 |
| Total Revenue and Other Income growth | -36.3% | -62.3% | -21.8% | -10.6% | 2.7% | -8.6% | -8.9% | 13.4% |
| Operating and Other Costs | 33.9 | 24.8 | 48.3 | 52.6 | 54.0 | 58.5 | 52.1 | 55.3 |
| Depreciation, Depletion and Amortization | 12.3 | 11.5 | 11.9 | 12.2 | 11.1 | 11.3 | 11.2 | 11.0 |
| Freight Expense | 3.2 | 0.8 | 0.8 | 1.4 | 0.9 | 1.0 | 1.7 | 1.4 |
| Selling, General and Administrative Expenses | 2.9 | 2.4 | 4.0 | 2.5 | 2.8 | 3.0 | 4.6 | 3.7 |
| Interest Expense, Net | -2.5 | -2.3 | -2.2 | -2.1 | -1.6 | -1.6 | -1.4 | -0.9 |
| Total Costs | 54.8 | 41.7 | 67.2 | 70.8 | 70.4 | 75.3 | 70.9 | 72.7 |
| Net (Loss) Income | -5.5 | -7.9 | 0.2 | 9.0 | 7.0 | 14.4 | 15.2 | 16.6 |
| Less: General Partner Interest in Net (Loss) Income | -0.1 | -0.1 | 0.0 | 0.2 | 0.1 | 0.2 | 0.3 | 0.3 |
| Limited Partner Interest in Net Income | -5.4 | -7.7 | 0.2 | 8.8 | 6.9 | 14.1 | 15.0 | 16.3 |
| Net (Loss) Income per Limited Partner Unit - Basic (in dollars per share) | 0.0 | 0.0 | | | 0.0 | 0.0 | | |
| |
| Net Income Per Limited Partner Unit - Diluted (in dollars per share) | ($0.20) | ($0.28) | $0.01 | $0.32 | $0.25 | $0.51 | $0.54 | $0.59 |
| |
| Limited Partner Units Outstanding - Basic (in shares) | 27.7 | 27.7 | 27.7 | 27.6 | 27.6 | 27.6 | 27.6 | 27.5 |
| Limited Partner Units Outstanding - Diluted (in shares) | 27.7 | 27.7 | 27.7 | 27.7 | 27.7 | 27.7 | 27.6 | 27.6 |
| Cash Distributions Declared per Unit (in dollars per share) | | | | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |