| 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 | 10-K |
| Cash flows from operating activities | | | | | | | | |
| Net income | 661.5 | 312.4 | 128.6 | 224.3 | 160.7 | 200.9 | 838.2 | 258.3 |
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| Adjustments to reconcile net income to net cash from operating activities: | | | | | | | | |
| Depreciation and amortization | 577.0 | 420.7 | 367.2 | 336.3 | 300.9 | 264.0 | 250.1 | 240.9 |
| Loss on early retirement of debt | | | 0.2 | 12.0 | | 0.3 | | |
| Gain on sale of operating property | -36.4 | -174.4 | -0.4 | -49.9 | | -43.2 | -295.4 | -104.3 |
| Distributions of income from joint ventures | 3.0 | 9.6 | 8.4 | 14.8 | 7.7 | 6.9 | 7.1 | 6.4 |
| Equity in income of joint ventures | | | | -14.8 | -7.8 | -6.8 | -7.1 | -6.2 |
| Share-based compensation | 12.8 | 15.4 | 13.9 | 15.2 | 16.7 | 17.5 | 20.1 | 17.7 |
| Net change in operating accounts and other | 3.9 | 3.5 | 9.5 | 38.1 | 9.6 | -4.8 | 0.3 | -5.8 |
| Net cash from operating activities | 744.7 | 577.5 | 519.3 | 555.6 | 503.7 | 434.7 | 443.1 | 423.2 |
| |
| Cash flows from investing activities | | | | | | | | |
| Development and capital improvements, including land | -449.4 | -428.7 | -427.2 | -407.6 | -359.2 | -299.1 | -343.0 | -411.8 |
| Acquisition of joint venture interests, net of cash acquired | -1,066.1 | -630.0 | | -436.3 | -290.0 | -58.3 | | |
| Other | -6.8 | 3.6 | 4.4 | 1.0 | 2.0 | -2.2 | 3.2 | -12.7 |
| Net cash from investing activities | -1,456.2 | -804.4 | -429.6 | -792.4 | -640.9 | -189.8 | 690.4 | -293.2 |
| |
| Cash flows from financing activities | | | | | | | | |
| Borrowings on unsecured revolving credit facility | 758.0 | | 358.0 | 1,217.0 | 342.0 | 465.0 | 1,305.0 | 1,466.0 |
| Repayments on unsecured revolving credit facility | -716.0 | | -402.0 | -1,173.0 | -342.0 | -465.0 | -1,549.0 | -1,222.0 |
| Repayment of notes payable, including prepayment penalties | -350.0 | | -100.0 | -746.7 | -381.4 | -279.0 | -3.1 | -253.0 |
| Proceeds from issuance of common shares | 516.8 | 759.2 | | 353.2 | | 445.0 | | |
| Distributions to common shareholders and non-controlling interests | -396.8 | -343.0 | -333.4 | -317.3 | -298.0 | -280.8 | -663.4 | -253.1 |
| Other | 8.9 | 6.5 | 3.2 | 3.5 | 2.5 | 2.8 | | -1.6 |
| Net cash from financing activities | 109.9 | 421.4 | 307.3 | 220.7 | -197.0 | -112.9 | -904.2 | -273.2 |
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| Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract] | | | | | | | | |
| Cash and cash equivalents | | | | | | | | |
| Restricted cash | | | | | | | | |
| |
| Supplemental information | | | | | | | | |
| Cash paid for interest, net of interest capitalized | 111.1 | 97.3 | 90.3 | 71.2 | 81.3 | 88.7 | 93.3 | 96.2 |
| Cash paid for income taxes | 3.2 | 2.2 | 2.3 | 1.3 | 2.0 | 1.7 | 2.4 | 1.9 |
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| Supplemental schedule of noncash investing and financing activities | | | | | | | | |
| Distributions declared but not paid | | | | | | | | |
| Value of shares issued under benefit plans, net of cancellations | 21.5 | 18.6 | 19.6 | 18.2 | 17.3 | 18.1 | 19.0 | 18.3 |
| Accrual associated with construction and capital expenditures | 20.2 | 24.3 | 29.6 | 27.2 | 35.6 | | | |