| 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 |
| Cash flows from operating activities: | | | | | | | | |
| Net loss | -20.6 | -7.8 | -15.5 | 7.0 | -12.3 | -4.4 | -3.0 | -3.1 |
| Adjustments to reconcile net loss to net cash used in operating activities: | | | | | | | | |
| Stock-based compensation expense | 1.4 | 1.1 | -0.6 | 2.0 | 3.2 | 2.4 | 1.7 | 1.7 |
| Depreciation and amortization | 1.6 | 2.5 | 2.9 | 3.3 | 2.8 | 2.1 | 2.3 | 3.3 |
| Provision for doubtful accounts | 0.2 | 0.0 | 0.1 | -0.2 | 0.1 | -0.1 | 0.4 | 1.4 |
| Changes in operating assets and liabilities: | | | | | | | | |
| Accounts receivable | 3.4 | -2.6 | 0.2 | 2.8 | 1.8 | 4.1 | 2.4 | 1.6 |
| Prepaid expenses and other current assets | -0.8 | 1.5 | -0.5 | -0.4 | 0.6 | 0.9 | 0.9 | 1.2 |
| Other assets | -0.2 | 0.0 | 0.2 | 0.2 | 0.8 | 0.7 | 0.5 | 0.5 |
| Accounts payable | 2.3 | 0.4 | -0.9 | -1.6 | 2.1 | -1.1 | -5.1 | -1.1 |
| Accrued liabilities | -0.2 | -0.6 | -1.9 | -3.4 | -0.3 | -0.8 | -5.3 | -0.9 |
| Deferred revenue | 1.3 | -0.1 | 2.0 | -0.3 | -1.2 | -0.4 | 0.4 | -0.4 |
| Other liabilities | -0.1 | 0.1 | 0.2 | 0.8 | -0.2 | -0.3 | -0.3 | -0.2 |
| Net cash used in operating activities | -11.5 | -5.5 | -13.6 | -14.8 | -2.4 | 3.5 | -5.5 | 2.0 |
| |
| Cash flows from investing activities: | | | | | | | | |
| Purchases of property and equipment | -0.8 | -0.6 | -0.8 | -1.3 | -2.3 | -4.5 | -1.8 | -3.0 |
| Net cash used in investing activities | -0.8 | -0.6 | 0.7 | 25.5 | -1.6 | -3.5 | -0.7 | -0.4 |
| |
| Cash flows from financing activities: | | | | | | | | |
| Net proceeds from issuance of common stock | 1.2 | | | 0.2 | 1.5 | 1.4 | 0.9 | 0.4 |
| Net cash provided by financing activities | 1.4 | 1.8 | -0.6 | -0.9 | 1.2 | 1.4 | 0.9 | -8.8 |
| Net decrease in cash and cash equivalents | -10.9 | -4.2 | -13.5 | 9.8 | -2.8 | 1.4 | -5.3 | -7.2 |
| Cash and cash equivalents at beginning of period | 16.1 | 20.3 | 33.8 | 24.0 | 26.8 | 25.4 | 30.7 | 38.0 |
| Cash and cash equivalents at end of period | 5.2 | 16.1 | 20.3 | 33.8 | 24.0 | 26.8 | 25.4 | 30.7 |
| |
| Supplemental Cash Flow Disclosure: | | | | | | | | |
| Net cash paid for taxes | 0.2 | 0.2 | 0.2 | 0.3 | 0.3 | 0.4 | 0.6 | -0.8 |
| Supplemental Non-cash Disclosure: | | | | | | | | |
| Fair value of warrants issued in connection with debt financing | | | | | | | | |
| Derivative Liability | | | | | | | | |