| In millions, except per share items | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 | Dec-31-11 | Dec-31-10 | Dec-31-09 | Dec-31-08 |
| | 10-K | 10-K | 10-K | 10-K/A | 10-K | 10-K | 10-K/A | 10-K/A |
| Net income | 6.9 | 150.5 | -1.5 | -40.0 | -92.7 | -135.1 | 0.0 | -59.8 |
| Depreciation and amortization [+] | 3.6 | 3.8 | 3.6 | 3.8 | 3.3 | 3.6 | | 3.5 |
| Depreciation | 2.2 | 2.4 | 2.2 | | 2.4 | 2.9 | | |
| Amortization | 1.4 | 1.4 | 1.4 | | 0.9 | 0.8 | | |
| Stock-based compensation | 2.5 | 0.9 | 0.7 | 0.0 | 0.0 | 0.1 | | 0.7 |
| Deferred taxes | 7.1 | -142.5 | 1.3 | -1.0 | 0.6 | | | -5.1 |
| Change in working capital [+] | -7.7 | -144.3 | -34.9 | | 78.5 | 53.4 | | 2.4 |
| Accounts receivable | | | | | | | | 2.4 |
| Other | -7.7 | -144.3 | -34.9 | | 78.5 | 53.4 | | |
| Other operating activities | -13.0 | 132.4 | 26.2 | -33.8 | 32.1 | 97.6 | | 62.2 |
| Cash from operations | -0.6 | 0.8 | -4.5 | -71.0 | 21.8 | 19.6 | | 4.0 |
| |
| Capital expenditures [+] | -2.3 | -2.0 | -3.3 | -2.9 | -2.7 | -0.8 | | -8.8 |
| Purchases of property and equipment | -2.3 | -2.0 | -3.3 | -2.9 | -2.7 | -0.8 | | -8.8 |
| Sales of property and equipment | 2.0 | 0.3 | 0.9 | | 0.3 | | | |
| Acquisitions | | | | -0.9 | | | | |
| Sales of short-term investments, net [+] | -31.8 | 91.1 | 125.7 | | 65.1 | 29.7 | | |
| Purchases of short-term investments | -89.1 | | -127.8 | | -302.8 | -291.3 | | |
| Sales of short-term investments | 57.3 | 91.1 | 253.5 | | 368.0 | 321.1 | | |
| Other cash from investing | -142.0 | -129.6 | -146.4 | | 364.7 | | | |
| Cash from investing | -174.1 | -40.1 | -23.1 | -63.9 | 427.5 | 164.1 | | -216.2 |
| |
| Cash dividends paid | | | | | -0.8 | | | -5.7 |
| Other cash from financing | 117.9 | 67.8 | -144.6 | -213.9 | -87.7 | -63.4 | | 208.2 |
| Cash from financing | 117.9 | 67.8 | -144.6 | -213.9 | -88.4 | -63.4 | | 202.5 |
| |
| Free cash flow | -2.9 | -1.2 | -7.8 | -73.9 | 19.2 | 18.9 | | -4.8 |
| Per share (diluted) | ($0.12) | ($0.06) | ($0.36) | ($3.46) | $4.56 | $165.31 | | ($0.42) |
| |
| Cash paid for interest | 13.4 | 9.1 | 10.1 | | 24.2 | 30.5 | | |
| Cash paid for income taxes | 0.0 | | 0.1 | | | 0.6 | | |