| In millions, except per share items | Jun-30-23 | Mar-31-23 | Dec-31-22 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 |
| | 10-Q | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q |
| Revenues | | | | | | | | |
| Operating revenue | 494.6 | 501.7 | 448.6 | 632.7 | 497.2 | 400.1 | 548.4 | 188.4 |
| Vessel charter revenue | 65.8 | 76.5 | 96.7 | 92.9 | 75.1 | 92.4 | 87.6 | 78.7 |
| Other revenue | 0.9 | 0.9 | 1.0 | 6.4 | 12.5 | 12.6 | 12.6 | 37.6 |
| Total revenues | 561.3 | 579.1 | 546.4 | 731.9 | 584.9 | 505.1 | 648.6 | 304.7 |
| Total revenues growth | -4.0% | 14.7% | -15.8% | 140.2% | 161.3% | 246.7% | 345.2% | 122.6% |
| Operating expenses | | | | | | | | |
| Cost of sales | 225.8 | 184.9 | | | 272.4 | 208.3 | | |
| Vessel operating expenses | 33.7 | 26.7 | 40.1 | 22.0 | 20.5 | 23.2 | 18.4 | 20.1 |
| Operations and maintenance | 33.7 | 26.7 | 40.1 | 22.0 | 20.5 | 23.2 | 18.4 | 20.1 |
| Selling, general and administrative | 55.8 | 52.1 | 70.1 | 67.6 | 50.3 | 48.0 | 74.9 | 46.8 |
| Transaction and integration costs | 1.6 | 0.5 | 9.4 | 5.6 | 4.9 | 1.9 | 2.1 | 1.8 |
| Depreciation and amortization | 42.1 | 34.4 | 36.2 | 35.8 | 36.4 | 34.3 | 30.3 | 31.2 |
| Asset impairment expense | | | 2.6 | | 48.1 | | | |
| Total operating expenses | 370.4 | 311.9 | 295.9 | 545.2 | 451.2 | 338.7 | 429.1 | 250.7 |
| Operating income | 191.0 | 267.2 | 250.5 | 186.7 | 133.7 | 166.5 | 219.5 | 53.9 |
| Operating margin | 34.0% | 46.1% | 45.8% | 25.5% | 22.9% | 33.0% | 33.8% | 17.7% |
| Interest expense | -64.4 | -71.7 | -80.5 | -63.6 | -47.8 | -44.9 | -46.6 | -57.6 |
| Other (income) expense, net | -6.6 | 25.0 | -16.4 | 10.2 | -22.1 | -19.7 | -3.7 | -5.4 |
| Income before income from equity method investments and income taxes | 133.2 | 170.5 | 186.4 | 97.9 | 108.0 | 141.3 | 165.6 | 1.7 |
| Income (loss) from equity method investments | 2.3 | 10.0 | -117.8 | -31.7 | -372.9 | 50.2 | -8.5 | -16.0 |
| Tax provision (benefit) | 15.3 | 29.0 | 2.8 | 10.0 | -86.5 | -49.7 | 5.4 | 3.5 |
| Tax rate | 11.5% | 17.0% | 1.5% | 10.2% | | | 3.3% | 202.6% |
| Net income (loss) | 120.1 | 151.6 | 65.8 | 56.2 | -178.4 | 241.2 | 151.7 | -17.8 |
| Net (income) loss attributable to non-controlling interest | -0.9 | -1.4 | -1.7 | 5.6 | 8.7 | -2.9 | -0.9 | 8.0 |
| Net income (loss) attributable to stockholders | 119.2 | 150.2 | 64.1 | 61.8 | -169.8 | 238.3 | 150.9 | -9.8 |
| |
| Net income (loss) per share - basic (in dollars per share) | $0.58 | $0.72 | $0.31 | $0.30 | ($0.81) | $1.14 | $0.76 | ($0.05) |
| Net income (loss) per share - diluted (in dollars per share) | $0.58 | $0.71 | $0.31 | $0.29 | ($0.81) | $1.13 | $0.74 | ($0.05) |
| |
| Weighted average number of shares outstanding, basic (in shares) | 205.0 | 208.7 | 209.5 | 209.6 | 209.7 | 209.9 | 198.6 | 207.5 |
| Weighted average number of shares outstanding - diluted (in shares) | 205.7 | 209.3 | 209.9 | 209.8 | 209.7 | 210.1 | 201.7 | 207.5 |
| |
| Other comprehensive income (loss): | | | | | | | | |
| Net income (loss) | 120.1 | 151.6 | 65.8 | 56.2 | -178.4 | 241.2 | 151.7 | -17.8 |
| Currency translation adjustment | 16.9 | 2.1 | 20.4 | -33.1 | -39.7 | 120.8 | 20.2 | 77.0 |
| |
| Comprehensive income (loss) | | | | | | | | |
| Comprehensive (income) loss attributable to non-controlling interest | | | | | | | | |
| Comprehensive income (loss) attributable to stockholders | 136.3 | 152.2 | 85.9 | 29.2 | -208.3 | 357.1 | 124.1 | -86.6 |