| In millions, except per share items | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 | Dec-31-13 | Dec-31-12 | Dec-31-11 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | -138.8 | -46.5 | -24.4 | -36.8 | -24.1 | -27.1 | -2.3 | -1.6 |
| Depreciation and amortization [+] | 34.8 | 1.5 | 1.3 | 1.4 | 1.3 | 1.4 | 1.4 | 1.3 |
| Depreciation | 29.0 | 1.5 | 1.3 | 1.4 | 1.3 | 1.4 | 1.4 | 1.3 |
| Amortization of intangible assets | 5.8 | | | | | | | |
| Stock-based compensation | 7.7 | 2.8 | 2.7 | 0.6 | 0.6 | 0.4 | 0.6 | 1.2 |
| Change in working capital [+] | 23.6 | 1.8 | 6.6 | 2.0 | -1.3 | -0.7 | 0.7 | 0.8 |
| Restricted cash | -0.8 | | | 0.4 | -0.6 | 0.1 | 0.0 | 0.9 |
| Accounts receivable | -4.7 | -0.4 | 0.2 | -0.1 | 0.1 | -0.1 | 0.4 | -0.3 |
| Other current assets | -4.7 | 0.8 | 0.5 | -0.5 | -1.3 | -0.2 | -0.1 | 0.0 |
| Accounts payable | 7.2 | 0.4 | 1.0 | -1.0 | -0.4 | -0.3 | 0.7 | 0.2 |
| Other | 26.5 | 0.9 | 4.8 | 3.3 | 0.8 | -0.3 | -0.4 | 0.0 |
| Other operating activities | 6.0 | 6.1 | 0.5 | 1.4 | 8.0 | 21.7 | 2.6 | 1.6 |
| Cash from operations | -66.7 | -34.3 | -13.2 | -31.4 | -15.5 | -4.3 | 3.0 | 3.3 |
| |
| Capital expenditures | -204.5 | -300.3 | -157.3 | -4.1 | -1.5 | -1.0 | -0.5 | -0.7 |
| Purchases of property and equipment | -204.5 | -300.3 | -157.3 | -4.1 | -1.5 | -1.0 | -0.5 | -0.7 |
| Other cash from investing | 128.4 | -116.4 | -68.0 | -16.2 | 0.0 | -5.5 | -8.0 | -0.8 |
| Cash from investing | -76.1 | -416.7 | -225.3 | -20.3 | -1.5 | -6.6 | -8.6 | -1.5 |
| |
| Cash dividends paid | -0.1 | -0.1 | -0.3 | | | | | |
| Issuance of common stock, net | | | 286.0 | 49.5 | 13.2 | 11.2 | | |
| Option exercises | 0.1 | 0.0 | 0.1 | 2.7 | 2.8 | 1.0 | 0.0 | |
| Financing costs | -0.6 | -23.9 | -1.3 | | | | | |
| Other cash from financing | 139.1 | 441.9 | -33.2 | 4.8 | 5.5 | -0.8 | 0.0 | -0.2 |
| Cash from financing | 139.5 | 465.6 | 253.7 | 51.7 | 16.0 | 9.4 | 0.0 | -0.2 |
| |
| Free cash flow | -271.2 | -334.6 | -170.5 | -35.5 | -17.0 | -5.4 | 2.5 | 2.6 |
| Per share (diluted) | ($8.25) | ($10.80) | ($6.04) | ($3.30) | ($1.83) | ($0.63) | $0.08 | $0.09 |
| |
| Cash paid for interest | 43.1 | 38.8 | 0.4 | 1.4 | 1.3 | 1.3 | 1.0 | 1.3 |