| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Cash flows from operating activities | | | | | | | | |
| Net income (loss) | 15.2 | 26.3 | 46.6 | 88.2 | 53.2 | 23.5 | 56.3 | 46.4 |
| |
| Adjustments to reconcile net income to net cash from operating activities: | | | | | | | | |
| Depreciation | 10.5 | 10.5 | 11.2 | 12.1 | | | | |
| Amortization of deferred financing costs | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | |
| Benefit for deferred income taxes | -1.8 | -10.5 | -0.6 | -5.1 | -1.3 | -13.7 | -5.3 | -3.7 |
| Change in fair value of equity securities | 8.3 | 0.9 | 0.2 | -6.3 | 13.2 | | | |
| Change in fair value of derivative instruments | -0.3 | 0.6 | -0.4 | 0.0 | -2.1 | 2.2 | 3.6 | -3.3 |
| Loss on disposal of property and equipment | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.2 | 0.1 | 0.2 |
| Noncash interest expense | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
| Changes in operating assets and liabilities: | | | | | | | | |
| Accounts receivable | 3.1 | -7.9 | 88.9 | -94.0 | 5.7 | 2.4 | 22.0 | 3.8 |
| Accounts receivable – related parties | 0.1 | 1.4 | 3.2 | -2.8 | -1.7 | 0.2 | -0.4 | 1.2 |
| Inventory | 0.2 | 7.0 | 3.7 | 1.7 | 4.5 | 8.3 | 12.9 | -19.6 |
| Income tax receivable | 7.8 | 7.9 | -9.6 | -1.2 | 0.1 | 13.6 | -6.4 | 5.6 |
| Prepaid expenses | -0.1 | 0.4 | -2.0 | -0.2 | -0.1 | 0.0 | -0.1 | 0.0 |
| Prepaid expenses - related parties | 0.0 | 0.0 | 0.0 | | | | 0.0 | 0.0 |
| Other assets | 0.8 | 0.7 | 0.7 | 0.2 | -0.3 | 0.0 | -0.6 | -0.7 |
| Accounts payable | 13.8 | 2.1 | -48.6 | 41.5 | 1.2 | -4.4 | -11.6 | 4.1 |
| Accounts payable - related parties | -0.1 | 6.9 | -0.3 | -0.4 | 0.5 | -0.1 | 1.0 | -2.7 |
| Accrued expenses and other current liabilities | -0.9 | 0.9 | 0.5 | 1.1 | 0.3 | 0.1 | -0.6 | -1.7 |
| Accrued expenses and other current liabilities – related parties | | 0.0 | -0.1 | 0.1 | | -0.1 | | |
| Deferred revenue | -4.1 | -2.9 | -0.7 | 1.6 | -1.3 | -4.2 | | |
| Other noncurrent liabilities | -0.3 | -0.7 | -0.5 | -3.6 | 3.2 | -2.2 | 1.8 | -2.8 |
| Net cash used in operating activities | 52.5 | 44.1 | 96.4 | 34.6 | 85.6 | 39.3 | 91.0 | 39.6 |
| |
| Cash flows from investing activities | | | | | | | | |
| Collateralization of derivative instruments | -0.4 | -0.8 | 0.2 | -0.1 | 1.7 | -1.9 | -0.5 | 1.2 |
| Proceeds from the sale of marketable securities | 1.3 | 40.7 | 9.8 | 31.4 | 48.2 | 23.3 | 30.5 | 48.5 |
| Proceeds from the sale of property and equipment | 0.1 | | 0.1 | 0.0 | 0.0 | 0.0 | | 0.0 |
| Capital expenditures | -4.8 | -1.5 | -4.5 | -7.0 | -4.9 | -3.6 | -4.5 | -7.2 |
| Net cash provided by (used in) investing activities | -3.8 | 15.0 | 0.5 | 4.2 | 25.4 | -13.2 | -35.2 | 2.0 |
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| Cash flows from financing activities | | | | | | | | |
| Payment of dividends | -10.5 | -119.9 | -141.7 | -10.5 | -10.5 | -110.7 | -10.5 | -10.5 |
| Deferred financing costs | | | -0.5 | | | | | -0.7 |
| Net cash used in financing activities | -10.5 | -119.7 | -142.1 | -10.5 | -10.7 | -110.8 | -10.5 | -11.7 |
| Net change in cash and cash equivalents | 38.1 | -60.6 | -45.2 | 28.4 | | | | |
| Cash paid for income taxes | 0.1 | 0.1 | 0.7 | 2.4 | 9.2 | 0.1 | 1.0 | 13.4 |
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| Noncash investing and financing activities: | | | | | | | | |
| Noncash capital expenditures | 0.2 | 0.4 | | 0.2 | 0.4 | | 0.5 | |