| In millions, except per share items | Jun-30-23 | Dec-31-22 | Sep-30-22 | Jun-30-22 | Mar-31-22 | Dec-31-21 | Sep-30-21 | Jun-30-21 |
| | 10-Q | 10-K | 10-Q | 10-Q | 10-Q | 10-K | 10-Q | 10-Q |
| Cash Flows from Operating Activities: | | | | | | | | |
| Net income | | 387.9 | 134.8 | -46.5 | -134.3 | -134.7 | -216.9 | -135.1 |
| Items included in net income not affecting cash flows: | | | | | | | | |
| Depreciation and amortization | | 110.4 | 109.0 | 107.1 | 96.9 | 86.7 | 59.6 | 90.0 |
| Loss on write-down of vessels and other assets | | | | | 5.2 | | | 101.1 |
| Amortization of debt discount and other deferred financing costs | | 5.2 | 4.3 | 3.2 | 2.6 | 2.3 | 2.2 | 2.3 |
| Amortization of time charter hire contracts acquired | | | 1.5 | 3.1 | 2.8 | 2.4 | 1.7 | |
| Deferred financing costs write-off | | 1.3 | 0.6 | 0.3 | 0.1 | | | |
| Stock compensation | | 6.7 | 6.1 | 11.0 | 10.6 | 10.5 | 10.5 | 5.4 |
| Earnings of affiliated companies | | -10.3 | | -21.0 | -22.0 | -21.8 | -5.0 | -4.6 |
| Other - net | | -2.2 | 1.0 | 1.8 | 3.1 | 3.0 | 2.0 | 2.1 |
| Items included in net income/(loss) related to investing and financing activities: | | | | | | | | |
| Gain on disposal of vessels and other assets, net | | -21.3 | -15.7 | -24.9 | -16.3 | -13.3 | -8.5 | 1.7 |
| Loss on sale of investment in affiliated companies | | | 9.5 | 9.5 | | | | |
| Cash distributions from affiliated companies | | 3.1 | | | 9.3 | 9.8 | 2.9 | 3.0 |
| Payments for drydocking | | -43.3 | -54.9 | -53.5 | -51.4 | -42.4 | -33.6 | -27.8 |
| Insurance claims proceeds related to vessel operations | | 5.3 | 5.2 | 3.2 | 2.3 | 1.8 | 1.7 | 5.4 |
| Changes in operating assets and liabilities: | | | | | | | | |
| Decrease/(increase) in receivables | | -182.7 | -133.3 | -83.7 | -27.1 | -16.5 | 21.8 | 49.9 |
| Decrease in deferred revenue | | 2.6 | 0.2 | | | -1.6 | 0.5 | |
| Net change in inventories, prepaid expenses and other current assets and accounts payable, accrued expense, and other current and long-term liabilities | | 13.1 | 12.9 | 3.1 | 4.9 | -3.6 | -10.0 | -6.8 |
| Net cash provided by operating activities | | 287.8 | 79.0 | -38.8 | -75.0 | -76.2 | -31.7 | 65.9 |
| |
| Cash Flows from Investing Activities: | | | | | | | | |
| Expenditures for other property | | -0.7 | -1.2 | -1.2 | -1.2 | -1.0 | -0.5 | -0.4 |
| Proceeds from sale of investment in affiliated companies | | | 139.0 | 140.1 | | | | |
| Investments in short term time deposits | | -105.0 | -80.0 | | | | | |
| Net cash (used in)/provided by investing activities | | 42.8 | 69.2 | 318.9 | 122.1 | 133.3 | 179.5 | 39.1 |
| |
| Cash Flows from Financing Activities: | | | | | | | | |
| Issuance of debt, net of issuance and deferred financing costs | | | | | | | | |
| Borrowings on long term debt, net of lenders' fees and deferred financing costs | | 640.1 | | 724.8 | | 83.7 | 59.5 | |
| Repayments of debt | | -798.7 | -1,363.3 | -1,306.4 | -639.2 | -619.3 | -438.3 | -484.4 |
| Proceeds from sale and leaseback financing, net of issuance and deferred financing costs | | 108.0 | 88.8 | 60.1 | 20.4 | | | |
| Payments of deferred financing costs | | 0.0 | 165.9 | -0.5 | | 0.0 | -166.6 | 0.0 |
| Cash dividends paid | | -69.8 | -17.8 | -46.5 | -42.2 | -40.9 | -39.6 | -6.7 |
| Repurchases of common stock | | | -36.7 | | | -16.7 | | |
| Cash paid to tax authority upon vesting or exercise of stock-based compensation | | -6.1 | -3.2 | -1.6 | -1.6 | | -1.4 | -1.4 |
| Net cash used in by financing activities | | -185.8 | -105.3 | -181.9 | -143.9 | -173.8 | -168.9 | -115.9 |