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/A | 10-K |
Net sales | 646.1 | 583.3 | 454.2 | 419.3 | 542.1 | 475.7 | 331.7 | 477.0 |
Net sales growth | 10.8% | 28.4% | 8.3% | -22.6% | 14.0% | 43.4% | -30.5% | 21.4% |
Cost of sales | 383.0 | 341.0 | 259.9 | 261.2 | 348.4 | 299.5 | 198.6 | 299.8 |
Gross profit | 263.1 | 242.3 | 194.3 | 158.2 | 193.7 | 176.2 | 133.1 | 177.2 |
Gross margin | 40.7% | 41.5% | 42.8% | 37.7% | 35.7% | 37.0% | 40.1% | 37.2% |
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Operating expenses, net: | | | | | | | | |
Research and development | 103.6 | 88.7 | 79.0 | 90.6 | 97.8 | 82.0 | 81.0 | 78.5 |
Selling, general, and administrative | 89.0 | 84.5 | 76.3 | 79.7 | 92.1 | 100.3 | 77.6 | 90.2 |
Amortization of intangible assets | 10.0 | 12.3 | 15.3 | 17.1 | 32.4 | 35.5 | 19.2 | 27.6 |
Other operating expense (income), net | 0.3 | 0.1 | -0.2 | 0.0 | 0.4 | -0.4 | 0.2 | -0.7 |
Total operating expenses, net | 202.9 | 185.6 | 171.7 | 197.8 | 609.2 | 248.1 | 253.3 | 200.5 |
Operating income | 60.3 | 56.7 | 22.6 | -39.6 | -415.5 | -71.9 | -120.2 | -23.2 |
Operating margin | 9.3% | 9.7% | 5.0% | -9.4% | -76.6% | -15.1% | -36.2% | -4.9% |
Interest income | 2.2 | 2.3 | 1.6 | 4.7 | 3.2 | 2.3 | 1.2 | 1.1 |
Interest expense | -11.5 | -28.4 | -24.7 | -22.1 | -21.5 | -19.5 | -0.2 | -0.5 |
Other income (expense), net | | -5.0 | -7.8 | -21.0 | | | | |
Income tax expense (benefit) | -116.0 | -0.4 | -0.1 | 0.8 | -26.7 | -37.6 | 2.8 | 9.3 |
Net income (loss) | 166.9 | 26.0 | -8.4 | -78.7 | -407.1 | | | |
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Income (loss) per common share: | | | | | | | | |
Basic (in dollars per share) | $3.35 | $0.53 | ($0.17) | ($1.66) | ($8.63) | ($1.16) | ($3.10) | ($0.80) |
Diluted (in dollars per share) | $2.71 | $0.49 | ($0.17) | ($1.66) | ($8.63) | ($1.16) | ($3.10) | ($0.80) |
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Weighted average number of shares: | | | | | | | | |
Basic (in shares) | 49.9 | 49.1 | 48.4 | 47.5 | 47.2 | 44.2 | 39.3 | 39.7 |
Diluted (in shares) | 65.6 | 53.6 | 48.4 | 47.5 | 47.2 | 44.2 | 39.3 | 39.7 |