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Share-Based Compensation - 2012 Equity Incentive Plan Narrative (Details) - 2021 Equity Incentive Plan - shares | 6 Months Ended |
--- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | May 31, 2021
Class A common shares/units |  |  |
Class of Stock [Line Items] |  |  |
Number of shares available to grant (in shares) |  |  | 9,544,095
Restricted share units |  |  |
Class of Stock [Line Items] |  |  |
Award vesting period | 3 years | 3 years |
Restricted share units | Non-Management Trustees |  |  |
Class of Stock [Line Items] |  |  |
Award vesting period | 1 year |  |
Performance Share Units (PSU's) |  |  |
Class of Stock [Line Items] |  |  |
Award vesting period | 3 years |  |
Service period | 3 years |  |
Performance Share Units (PSU's) | Minimum |  |  |
Class of Stock [Line Items] |  |  |
Percentage of units expected to vest (in percent) | 0.00% |  |
Performance Share Units (PSU's) | Maximum |  |  |
Class of Stock [Line Items] |  |  |
Percentage of units expected to vest (in percent) | 200.00% |  |

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- Definition Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition Percentage of vesting of award under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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