| In millions, except per share items | Dec-31-18 | Sep-30-18 | Jun-30-18 | Mar-31-18 | Dec-31-17 | Sep-30-17 | Jun-30-17 | Mar-31-17 |
| | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q |
| Net sales | 819.0 | 851.0 | 880.0 | 786.0 | 831.0 | 795.0 | 811.0 | 767.0 |
| Net sales growth | -1.4% | 7.0% | 8.5% | 2.5% | 13.2% | 3.7% | 5.5% | 2.7% |
| Gross profit | 131.0 | 152.0 | 184.0 | 139.0 | 167.0 | 162.0 | 168.0 | 159.0 |
| Gross margin | 16.0% | 17.9% | 20.9% | 17.7% | 20.1% | 20.4% | 20.7% | 20.7% |
| Selling and administrative expenses | 94.0 | 83.0 | 109.0 | 93.0 | 84.0 | 71.0 | 73.0 | 75.0 |
| Long-lived asset impairment charges | | | | | | | | |
| Recovery of receivable | | | | | | | | |
| Operating profit | 37.0 | 69.0 | 75.0 | 46.0 | 83.0 | 91.0 | 95.0 | 84.0 |
| Operating margin | 4.5% | 8.1% | 8.5% | 5.9% | 10.0% | 11.4% | 11.7% | 11.0% |
| Income from equity method investments | 9.0 | 12.0 | 12.0 | 9.0 | 17.0 | 15.0 | 14.0 | 13.0 |
| Interest expense | -14.0 | -14.0 | -15.0 | -14.0 | -15.0 | -15.0 | -19.0 | -20.0 |
| Interest income | 2.0 | 2.0 | 2.0 | 1.0 | 2.0 | 1.0 | | 1.0 |
| Loss on extinguishment of debt | | | | | | | -22.0 | |
| Other income, net | 4.0 | 4.0 | -3.0 | 3.0 | 5.0 | 1.0 | -2.0 | 6.0 |
| Income from continuing operations before income taxes | 75.0 | 58.0 | 58.0 | 36.0 | 168.0 | 66.0 | 46.0 | 55.0 |
| Income tax expense | -71.0 | 15.0 | 13.0 | 9.0 | -314.0 | 27.0 | 20.0 | 29.0 |
| Income from continuing operations | 39.0 | 59.0 | 58.0 | 37.0 | -60.0 | 66.0 | 36.0 | 55.0 |
| Income (loss) from discontinued operations, net of tax | 1.0 | 1.0 | | 1.0 | 1.0 | | -10.0 | |
| Gain on sale of discontinued operations, net of tax | | | | | | | | |
| Net income | 42.0 | 59.0 | 58.0 | 37.0 | -69.0 | 66.0 | 36.0 | 55.0 |
| |
| Earnings per common share - basic: | | | | | | | | |
| Income from continuing operations (in dollars per share) | 0.0 | 0.0 | 0.0 | | 0.0 | 0.0 | 0.0 | |
| Income | 0.0 | | | | 0.0 | | 0.0 | |
| |
| Net income (in dollars per share) | $0.31 | $0.42 | $0.41 | $0.26 | ($0.48) | $0.47 | $0.25 | $0.38 |
| |
| Earnings per common share - diluted: | | | | | | | | |
| Income from continuing operations (in dollars per share) | 0.0 | 0.0 | 0.0 | | 0.0 | 0.0 | 0.0 | |
| Income | 0.0 | | | | 0.0 | | 0.0 | |
| Net income (in dollars per share) | $0.31 | $0.41 | $0.41 | $0.25 | ($0.47) | $0.46 | $0.24 | $0.37 |
| |
| Average common shares (in shares) | 140.3 | 139.9 | 139.6 | 141.1 | 144.4 | 142.1 | 144.5 | 146.3 |
| |
| Dilutive awards under long-term incentive plan (in shares) | | | | | | | | |
| Average diluted common shares (in shares) | 142.6 | 142.9 | 140.9 | 143.8 | 146.7 | 144.7 | 146.9 | 148.7 |