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Employee Share-Based Incentive Compensation Plans - Performance Shares (Details) - Performance Shares - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Target Performance Shares Outstanding |  |  |
Beginning of period (in shares) | 42,458 | 42,473 | 40,616
Shares paid or expired (in shares) | (14,336) | (14,070) | (13,715)
New grants (in shares) | 13,475 | 14,055 | 15,600
Forfeitures and cancellations (in shares) | (769) | 0 | (28)
Expense recognized (in shares) | 0 | 0 | 0
End of period (in shares) | 40,828 | 42,458 | 42,473
Accrued Expense |  |  |
Beginning of period | $ 56.3 | $ 43.7 | $ 31.7
Shares paid or expired | (35.2) | (27.7) | (18.1)
New grants | 0.0 | 0.0 | 0.0
Forfeitures and cancellations | 0.4 | (0.4) | (0.1)
Expense recognized | 20.7 | 40.7 | 30.2
End of period | $ 42.2 | $ 56.3 | $ 43.7
Range Of Performance Cycle From 2018 to 2020 | W T M Incentive and Phantom Plan |  |  |
Accrued Expense |  |  |
Payout for maximum growth target percentage | 200.00% |  |
Range Of Performance Cycle From 2017 to 2019 | W T M Incentive and Phantom Plan |  |  |
Accrued Expense |  |  |
Payout for maximum growth target percentage |  | 180.00% |
Payout for minimum growth target percentage |  | 174.00% |
Range Of Performance Cycle From 2016-2018 | W T M Incentive and Phantom Plan |  |  |
Accrued Expense |  |  |
Payout for maximum growth target percentage |  |  | 166.00%
Payout for minimum growth target percentage |  |  | 139.00%

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- Definition Amount of expense for award under share-based payment arrangement. Excludes amount capitalized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5047-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=122041274&loc=d3e301413-122809 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + 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 (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan). + 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 (c)(2)(iii)(1) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date. + 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 (c)(2)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition The amount of performance shares that were paid out (including deposits into a deferred compensation plan) or that expired due to failure to meet performance criteria. + References No definition available. + Details
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- Definition The number of target performance shares that were paid out (including deposits into a deferred compensation plan) or that expired due to failure to meet performance criteria. + References No definition available. + Details
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