| In millions, except per share items | Dec-31-22 | Dec-31-21 | Dec-31-20 | Dec-31-19 | Dec-31-18 | Dec-31-17 | Dec-31-16 | Dec-31-15 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Cash flows from operating activities: | | | | | | | | |
| Net loss | -7.6 | -20.8 | -0.7 | 2.0 | 34.9 | 48.9 | 24.2 | 33.2 |
| Adjustments to reconcile net loss to net cash flows from operating activities: | | | | | | | | |
| Provision for doubtful accounts | 6.7 | 4.9 | 5.0 | 5.8 | 5.1 | 4.0 | 2.5 | 1.2 |
| Amortization of debt discount and debt issuance costs | 2.0 | 1.3 | 0.5 | 0.5 | 0.8 | 0.7 | 0.5 | 0.5 |
| Loss on disposition of long-lived assets | 4.4 | 2.8 | 21.6 | 2.8 | -26.4 | 0.1 | 0.0 | -2.8 |
| Stock-based compensation | 7.4 | 6.6 | 5.9 | 6.4 | 6.4 | 7.0 | 6.4 | 5.0 |
| Changes in operating assets and liabilities, excluding the effects of acquisitions and dispositions: | | | | | | | | |
| Net cash provided by operating activities | 102.9 | 80.5 | 86.3 | 87.9 | 115.9 | 145.7 | 111.7 | 139.2 |
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| Cash flows from investing activities: | | | | | | | | |
| Acquisition of business net of cash acquired | | | | | | | | |
| Cash flows from financing activities: | | | | | | | | |
| Purchases of common stock - stock- based compensation | -1.2 | -1.7 | -1.7 | -1.6 | | | | |
| Noncash investing activity: | | | | | | | | |