| In millions, except per share items | Sep-30-20 | Jun-30-20 | Mar-31-20 | Dec-31-19 | Sep-30-19 | Jun-30-19 | Mar-31-19 | Dec-31-18 |
| | 10-Q | 10-Q | 10-Q | 8-K | 10-Q | 10-Q | 10-Q | 10-K |
| Net sales | 115.5 | 77.1 | 91.0 | 189.9 | 146.5 | 106.8 | 78.8 | 166.5 |
| Net sales growth | -21.2% | -27.8% | 15.5% | 14.0% | 3.8% | -9.9% | -29.7% | -5.9% |
| Cost of sales | 77.0 | 53.8 | 109.9 | | 92.1 | 69.0 | 54.9 | 108.1 |
| Gross profit | 38.4 | 23.3 | -18.9 | 67.4 | 54.3 | 37.8 | 23.8 | 58.5 |
| Gross margin | 33.3% | 30.2% | -20.8% | 35.5% | 37.1% | 35.4% | 30.3% | 35.1% |
| |
| Operating expenses: | | | | | | | | |
| Advertising and marketing | 3.2 | 2.4 | 4.4 | 6.0 | 4.1 | 4.5 | 4.6 | 3.7 |
| Selling, general, and administrative | 27.1 | 26.2 | 37.0 | 40.9 | 38.1 | 39.0 | 36.2 | 33.6 |
| Transaction costs | 0.1 | 0.1 | 0.3 | 0.8 | 0.5 | 0.4 | 0.2 | 1.0 |
| Impairment of goodwill | | | 18.6 | | | | | |
| Loss on disposal of intangible assets and equipment | | | 3.7 | | 0.1 | 0.0 | 0.0 | |
| Amortization of intangible assets | 3.4 | 3.4 | 3.5 | 4.0 | 3.9 | 4.6 | 4.5 | 3.5 |
| Total operating expenses | 30.5 | 29.6 | 63.2 | 45.6 | 42.7 | 44.0 | 40.9 | 38.1 |
| Income (loss) from operations | 7.9 | -6.3 | -82.2 | 21.8 | 11.7 | -6.2 | -17.1 | 20.3 |
| Operating margin | 6.9% | -8.1% | -90.3% | 11.5% | 8.0% | -5.8% | -21.7% | 12.2% |
| |
| Other income (expense): | | | | | | | | |
| Interest expense | -0.9 | -1.0 | -1.5 | -1.6 | -1.2 | -1.1 | -1.0 | -0.6 |
| Other income (expense) | 0.9 | 0.2 | 0.0 | -0.4 | -0.5 | 1.2 | -0.5 | -0.1 |
| Total other expense | 0.8 | -0.7 | -1.5 | -0.4 | -1.7 | 1.3 | -1.5 | -0.7 |
| Income (loss) before provision for income taxes | 7.9 | -7.0 | -83.7 | | 10.0 | -6.1 | -18.6 | 19.7 |
| Income tax (provision) benefit | -1.7 | 3.7 | 8.2 | 4.4 | -1.3 | 0.8 | 4.2 | -5.3 |
| Net income (loss) | 6.2 | -3.3 | -75.6 | 25.0 | 8.7 | -5.3 | -14.4 | 14.3 |
| |
| Earnings (loss) per share attributable to stockholders: | | | | | | | | |
| Basic earnings (loss) per share (in usd per share) | $0.21 | ($0.11) | ($2.54) | $0.86 | $0.30 | ($0.18) | ($0.50) | $0.52 |
| Diluted earnings (loss) per share (in usd per share) | $0.21 | ($0.11) | ($2.54) | $0.85 | $0.30 | ($0.18) | ($0.50) | $0.51 |