| 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 |
| Net income | 70.9 | 74.6 | 45.2 | 26.8 | 32.4 | 59.6 | 15.9 | -1.7 |
| Depreciation and amortization | 22.9 | 18.2 | 12.8 | 10.3 | 9.0 | 8.9 | 8.6 | 9.5 |
| Asset impairment charges | | | | | 0.1 | 3.0 | 0.4 | |
| Stock-based compensation | 0.4 | | 0.0 | 0.1 | 0.3 | 0.1 | 0.1 | 0.2 |
| Deferred taxes | 4.5 | 16.0 | 8.5 | 8.4 | -4.8 | -17.4 | 29.6 | 2.3 |
| Change in working capital [+] | -0.4 | -0.9 | 2.9 | 4.8 | -1.8 | 22.9 | -28.1 | 16.7 |
| Accounts receivable | | | | | | | | 21.8 |
| Income taxes | 0.0 | 0.3 | | | -5.0 | -0.1 | -0.9 | -1.7 |
| Other | -0.3 | -1.1 | 2.9 | 4.8 | 3.2 | 23.0 | -27.2 | -3.4 |
| Other operating activities | -50.1 | 3.9 | -32.2 | -19.9 | 6.3 | -23.4 | -15.8 | -4.5 |
| Cash from operations | 48.2 | 111.8 | 37.3 | 30.4 | 41.4 | 53.7 | 10.7 | 22.4 |
| |
| Capital expenditures [+] | -7.3 | -4.3 | -5.7 | -9.4 | -2.6 | -3.0 | -4.5 | -9.1 |
| Purchases of property and equipment | -7.3 | -4.3 | -5.7 | -9.4 | -2.6 | -3.0 | -4.5 | -9.1 |
| Sales of property and equipment | 0.0 | 0.0 | 0.0 | 0.1 | 5.0 | 2.5 | 0.0 | |
| Sales of short-term investments, net [+] | 243.0 | 276.1 | 11.0 | 7.0 | 3.1 | -80.8 | 60.5 | 385.7 |
| Purchases of short-term investments | 97.1 | 157.9 | | | -6.9 | -94.8 | -322.0 | |
| Sales of short-term investments | 145.9 | 118.2 | 11.0 | 7.0 | 10.0 | 14.0 | 382.5 | 385.7 |
| Other cash from investing | -425.5 | -467.9 | -180.6 | -28.1 | 38.6 | 125.7 | -35.0 | 68.8 |
| Cash from investing | -189.8 | -196.1 | -175.3 | -30.4 | 44.1 | 44.4 | 21.0 | 445.4 |
| |
| Cash dividends paid | -23.5 | -18.8 | -4.1 | | | | | |
| Repurchase of common stock, net | -20.0 | | -8.8 | -20.8 | -93.4 | -147.4 | -14.8 | -305.0 |
| Other cash from financing | 155.9 | 67.4 | 72.3 | 11.5 | 13.5 | -1.8 | 9.3 | 15.4 |
| Cash from financing | 112.5 | 48.6 | 59.4 | -9.4 | -79.9 | -149.2 | -5.6 | -289.6 |
| |
| Free cash flow | 40.9 | 107.5 | 31.6 | 21.0 | 38.8 | 50.7 | 6.1 | 13.3 |
| Per share (diluted) | $0.70 | $1.83 | $0.54 | $0.35 | $0.62 | $0.72 | $0.08 | $0.15 |
| |
| Cash paid for interest | 17.2 | 13.6 | 12.8 | 11.9 | 11.6 | 11.8 | 11.8 | 10.6 |
| Cash paid for income taxes | 17.1 | 11.1 | | | 2.0 | 5.4 | 2.3 | |