| In millions, except per share items | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 | Dec-31-11 | Dec-31-10 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | -469.3 | -472.0 | 39.0 | 57.4 | 101.3 | 55.9 | 65.5 | 250.4 |
| Depreciation and amortization | 109.4 | 88.3 | 68.6 | 34.0 | 36.0 | 77.9 | 15.7 | 12.7 |
| Asset impairment charges | 372.2 | 541.6 | 13.7 | | | | | |
| Stock-based compensation | 26.3 | 32.2 | 28.6 | 20.9 | 17.6 | 16.3 | 12.7 | 10.7 |
| Tax benefit from stock-based compensation | | | | -3.3 | -0.7 | -4.7 | -6.5 | -6.2 |
| Deferred taxes | | | | | | | | 42.9 |
| Change in working capital [+] | 66.0 | 64.1 | -23.4 | -72.2 | -15.4 | 65.8 | -109.5 | -113.1 |
| Accounts receivable | 12.6 | 26.8 | -121.1 | -33.5 | -20.7 | 61.5 | -71.9 | 103.5 |
| Inventories | 6.7 | -45.6 | -14.0 | -16.3 | 7.1 | -33.7 | -5.5 | 4.6 |
| Other current assets | -65.6 | -0.6 | 9.3 | -10.0 | -7.6 | -22.3 | -16.0 | -12.1 |
| Deferred revenues | | | -4.3 | -3.9 | -4.4 | -26.8 | -23.0 | -195.2 |
| Other | 112.4 | 83.4 | 106.7 | -8.5 | 10.3 | 87.1 | 6.9 | -13.8 |
| Other operating activities | -20.4 | -170.3 | -34.1 | | | | | |
| Cash from operations | 84.2 | 83.9 | 92.5 | 32.8 | 149.9 | 105.8 | 6.1 | 249.8 |
| |
| Capital expenditures [+] | -26.7 | -49.4 | -25.2 | -29.9 | -32.8 | -66.9 | -30.5 | -16.3 |
| Purchases of property and equipment | -26.7 | -49.4 | -25.2 | -29.9 | -32.8 | -66.9 | -30.5 | -16.3 |
| Sales of property and equipment | 21.5 | 1.4 | 59.5 | | | | | |
| Purchases of intangible assets | -0.1 | -3.5 | -5.9 | -13.0 | -12.0 | -104.8 | | |
| Acquisitions | -0.1 | -585.8 | -691.3 | | | | | |
| Sales of short-term investments, net [+] | | | 200.1 | 395.4 | -71.1 | 85.9 | 15.5 | -197.4 |
| Purchases of short-term investments | | | | | -357.1 | -210.7 | -359.6 | -403.1 |
| Sales of short-term investments | | | 200.1 | 395.4 | 286.0 | 296.6 | 375.1 | 205.7 |
| Other cash from investing | -4.2 | 10.3 | -4.8 | -369.1 | | | | |
| Cash from investing | -9.7 | -627.1 | -467.5 | -16.6 | -115.9 | -85.8 | -15.0 | -213.6 |
| |
| Option exercises | 1.4 | 9.2 | 11.5 | 11.1 | 8.2 | 12.6 | 14.8 | 17.7 |
| Financing costs | -0.8 | -11.9 | -36.9 | | | | | |
| Other cash from financing | -73.1 | 379.9 | 475.4 | 25.5 | | | | |
| Cash from financing | -73.7 | 382.5 | 500.9 | 14.4 | 9.0 | 17.3 | 21.3 | 23.9 |
| |
| Free cash flow | 57.5 | 34.4 | 67.3 | 2.9 | 117.2 | 38.9 | -24.4 | 233.5 |
| Per share (diluted) | $0.80 | $0.48 | $0.93 | $0.04 | $1.71 | $0.57 | ($0.36) | $3.56 |
| |
| Cash paid for interest | 28.4 | 18.1 | 15.4 | 0.0 | 0.1 | 0.5 | 0.2 | 0.2 |
| Cash paid for income taxes | 2.9 | 23.1 | 43.2 | 72.2 | 34.3 | | 24.4 | 129.8 |