| In millions, except per share items | Sep-30-20 | Sep-30-19 | Sep-30-18 | Sep-30-17 | Sep-30-16 | Sep-30-15 | Sep-30-14 | Sep-30-13 |
| | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K | 10-K |
| Net sales: | | | | | | | | |
| Net sales | 1,476.2 | 1,496.5 | 1,202.9 | 1,107.7 | 1,070.6 | 1,431.0 | 1,398.4 | 1,361.4 |
| Net sales growth | -1.4% | 24.4% | 8.6% | 3.5% | -25.2% | 2.3% | 2.7% | -3.0% |
| Costs and expenses: | | | | | | | | |
| Costs | | | | | | | | |
| Selling, general and administrative expenses | 274.7 | 270.1 | 258.6 | 240.2 | 253.2 | 212.5 | 181.7 | 165.2 |
| Research and development | 44.6 | 50.1 | 52.4 | 52.7 | 32.0 | 18.0 | 18.0 | 24.4 |
| Amortization of purchased intangibles | 59.3 | 42.1 | 27.1 | 30.2 | 29.4 | 27.6 | 22.6 | 16.7 |
| (Gain) loss on sale of property, plant and equipment | -0.2 | -32.5 | | 0.4 | | | | |
| Restructuring costs | 16.6 | 15.4 | 5.0 | 2.3 | 1.3 | 6.3 | 1.1 | 8.1 |
| Total costs and expenses | 1,414.7 | 1,410.2 | 1,178.5 | 1,105.1 | 1,082.3 | 1,355.7 | 1,305.9 | 1,320.7 |
| Operating loss | 61.6 | 86.2 | 24.4 | 2.6 | -11.6 | 75.4 | 92.5 | 40.7 |
| Operating margin | 4.2% | 5.8% | 2.0% | 0.2% | -1.1% | 5.3% | 6.6% | 3.0% |
| |
| Other income (expenses): | | | | | | | | |
| Interest and dividend income | 7.5 | 6.5 | 1.6 | 1.0 | 1.4 | 1.8 | 1.4 | 1.6 |
| Interest expense | -27.7 | -20.5 | -10.4 | -15.0 | -11.2 | -4.4 | -4.1 | -3.4 |
| Other income (expense), net | -28.8 | -20.0 | -0.7 | 0.4 | -2.3 | -0.9 | -0.4 | 0.9 |
| Loss from continuing operations before income taxes | -3.4 | 52.3 | 14.9 | -11.1 | -26.4 | 71.9 | 89.4 | 39.8 |
| Income tax provision (benefit) | -6.4 | 11.0 | 7.1 | 14.7 | -14.4 | 49.0 | 19.8 | 14.5 |
| Tax rate | 185.2% | 21.1% | 47.6% | | 54.3% | 68.1% | 22.2% | 36.5% |
| Loss from continuing operations | 2.9 | 41.3 | 7.8 | -25.7 | -12.1 | | | |
| Net income (loss) from discontinued operations | 0.4 | -1.4 | 4.2 | 14.5 | 13.8 | | | |
| Net loss | 3.4 | 81.2 | 12.0 | -36.9 | -10.3 | 22.9 | 69.6 | 25.3 |
| Less noncontrolling interest in net income (loss) of VIE | 6.6 | -9.8 | -0.3 | | | 0.0 | 0.1 | 0.2 |
| Net loss attributable to Cubic | -3.2 | 49.7 | 12.3 | -11.2 | 1.7 | 22.9 | | 25.3 |
| |
| Amounts attributable to Cubic: | | | | | | | | |
| Net loss from continuing operations | -3.7 | 51.1 | 8.1 | -25.7 | -12.1 | | | |
| Net loss from discontinued operations | 0.4 | -1.4 | 4.2 | 14.5 | 13.8 | | | |
| Net loss attributable to Cubic | -3.2 | 49.7 | 12.3 | -11.2 | 1.7 | 22.9 | | 25.3 |
| |
| Net loss per share: | | | | | | | | |
| Basic | | | | | | | | |
| Continuing operations attributable to Cubic (in dollars per share) | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | | | |
| Discontinued operations (in dollars per share) | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | | | |
| |
| Basic earnings per share attributable to Cubic (in dollars per share) | ($0.10) | $1.63 | $0.45 | ($0.41) | $0.06 | $0.85 | $2.59 | $0.94 |
| |
| Diluted | | | | | | | | |
| Continuing operations attributable to Cubic (in dollars per share) | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | | | |
| Discontinued operations (in dollars per share) | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | | | |
| Diluted earnings per share attributable to Cubic (in dollars per share) | ($0.10) | $1.62 | $0.45 | ($0.41) | $0.06 | $0.85 | $2.59 | $0.94 |
| |
| Weighted average shares used in per share calculations: | | | | | | | | |
| Basic (in shares) | 31.3 | 30.5 | 27.2 | 27.1 | 27.0 | 26.9 | 26.8 | 26.7 |
| Diluted (in shares) | 31.3 | 30.6 | 27.4 | 27.1 | 27.0 | 26.9 | 26.8 | 26.8 |