| In millions, except per share items | Jun-30-21 | Dec-31-20 | Sep-30-20 | Sep-05-20 | Jun-30-20 | Jun-05-20 | Mar-31-20 | Dec-31-19 |
| | 10-Q | 10-K | 10-Q | 8-K | 10-Q | 8-K | 10-Q | 10-K |
| Net sales | 221.7 | 210.3 | 207.1 | 207.1 | 146.2 | 146.2 | 200.5 | 193.3 |
| Net sales growth | 51.7% | 8.8% | 0.9% | 0.9% | -33.8% | -33.8% | -8.0% | -7.9% |
| Cost of sales | 174.0 | 170.3 | 169.2 | | 117.7 | | 162.0 | 164.6 |
| Gross profit | 47.8 | 40.0 | 37.9 | 37.9 | 28.4 | 28.4 | 38.6 | 28.7 |
| Gross margin | 21.6% | 19.0% | 18.3% | 18.3% | 19.4% | 19.4% | 19.2% | 14.9% |
| Selling, product development and administrative expenses | 38.2 | 34.5 | 32.2 | 47.2 | 30.2 | 30.2 | 33.0 | 32.3 |
| Impairment of goodwill and other long-lived assets | | | | | | | 61.1 | |
| Operating income (loss) | 9.4 | 4.5 | -9.3 | -9.3 | -1.7 | -1.7 | -55.6 | -68.5 |
| Operating margin | 4.2% | 2.2% | -4.5% | -4.5% | -1.2% | -1.2% | -27.7% | -35.4% |
| (Gain) loss on the sale of a business | 0.3 | | | | | | | |
| Interest expense | -2.4 | -4.1 | -4.5 | | -4.5 | | -2.9 | -3.2 |
| Other (income) expense, net | 0.2 | 2.1 | 0.3 | 0.3 | 0.2 | 0.2 | -0.4 | 0.1 |
| Income (loss) before income taxes | 6.5 | -1.6 | -14.1 | -14.1 | -6.5 | -6.5 | -58.4 | -71.4 |
| Income tax expense (benefit) | 0.9 | -1.9 | -2.3 | -2.3 | -0.6 | -0.6 | -2.0 | -0.9 |
| Tax rate | 13.9% | 115.3% | 16.6% | 16.6% | 9.2% | 9.2% | 3.5% | 1.3% |
| (Income) loss from equity method investment | -0.2 | 0.0 | -0.1 | 0.1 | 0.0 | | 0.0 | 0.0 |
| Net income (loss) | 5.8 | 0.3 | -11.7 | -11.7 | -5.9 | -5.9 | -56.4 | -70.5 |
| |
| Earnings (loss) per share: | | | | | | | | |
| Basic (in usd per share) | $0.33 | $0.02 | ($0.67) | ($0.67) | ($0.34) | ($0.34) | ($3.25) | ($4.08) |
| Diluted (in usd per share) | $0.32 | $0.02 | ($0.67) | ($0.67) | ($0.34) | ($0.34) | ($3.25) | ($4.08) |
| |
| Weighted average number of common shares outstanding: | | | | | | | | |
| Basic (in shares) | 17.6 | 17.4 | 17.4 | 17.4 | 17.4 | 17.4 | 17.3 | 17.3 |
| Diluted (in shares) | 18.0 | 17.4 | 17.4 | 17.4 | 17.4 | 17.4 | 17.3 | 17.3 |