| In millions, except per share items | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 | Dec-31-14 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net income | -35.5 | -5.8 | -1.8 | -0.9 | -1.5 | -6.9 | -17.2 | -21.2 |
| Depreciation and amortization | 12.0 | 7.1 | 5.6 | 4.5 | 4.2 | 3.8 | 2.5 | 1.7 |
| Stock-based compensation | 28.2 | 8.9 | 6.8 | 4.8 | 3.4 | 2.9 | 3.0 | 4.1 |
| Deferred taxes | 0.8 | | | | | | | |
| Change in working capital [+] | -60.4 | -36.2 | -19.1 | -9.3 | -7.4 | -0.6 | -1.7 | 0.7 |
| Accounts receivable | -66.2 | -43.3 | -22.8 | -11.2 | -10.2 | -1.8 | -0.3 | -0.1 |
| Other current assets | -3.1 | -2.8 | -0.4 | -2.6 | -0.2 | 0.0 | -0.9 | -0.4 |
| Accounts payable | 8.8 | 10.0 | 4.1 | 4.5 | 3.0 | 1.2 | -0.5 | 0.4 |
| Accrued expenses | | | | | | | | 0.6 |
| Other | | | | | | | | 0.2 |
| Other operating activities | 62.4 | 47.6 | 24.6 | 13.7 | 10.9 | 5.7 | 3.0 | 3.9 |
| Cash from operations | 7.5 | 21.5 | 16.2 | 12.7 | 9.7 | 5.0 | -10.4 | -10.8 |
| |
| Capital expenditures | -12.4 | -7.5 | -5.4 | -56.9 | -3.1 | -1.9 | -4.9 | -5.6 |
| Purchases of property and equipment | -12.4 | -7.5 | -5.4 | -56.9 | -3.1 | -1.9 | -4.9 | -5.6 |
| Purchases of intangible assets | | | | -3.0 | | | | |
| Acquisitions | | -48.1 | | | | | | |
| Sales of short-term investments | 57.9 | 44.1 | 49.8 | 35.4 | 23.4 | 27.2 | 20.2 | 28.6 |
| Sales of short-term investments | 57.9 | 44.1 | 49.8 | 35.4 | 23.4 | 27.2 | 20.2 | 28.6 |
| Other cash from investing | -97.4 | -65.2 | -72.4 | -57.0 | -33.3 | -31.8 | -25.2 | -34.9 |
| Cash from investing | -51.9 | -76.7 | -28.0 | -81.5 | -13.1 | -6.5 | -9.9 | -11.9 |
| |
| Issuance of common stock, net | | 192.3 | | 65.7 | | | | 72.8 |
| Option exercises | 3.6 | 6.0 | 3.0 | 3.6 | 2.5 | 3.7 | 1.3 | 0.2 |
| Financing costs | | | | | | | | -0.1 |
| Other cash from financing | 2.5 | -15.4 | 17.0 | 9.2 | 7.6 | 11.4 | -12.9 | -14.8 |
| Cash from financing | -1.1 | 170.8 | 14.0 | 71.2 | 5.1 | 7.7 | -14.2 | 57.9 |
| |
| Free cash flow | -4.9 | 14.1 | 10.8 | -44.3 | 6.5 | 3.1 | -15.3 | -16.4 |
| Per share (diluted) | ($0.12) | $0.39 | $0.31 | ($1.38) | $0.22 | $0.11 | ($0.55) | ($1.27) |
| |
| Cash paid for interest | 0.0 | 1.4 | 1.2 | 1.0 | 0.3 | 0.2 | 0.2 | 1.5 |