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Employee Share-Based Incentive Compensation Plans - Performance Shares (Details) - Performance Share - W T M Incentive Plan - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020
Target Performance Shares Outstanding |  |  |  |
Beginning of period (in shares) | 40,784 | 42,458 | 42,458 | 42,473
Shares paid (in shares) | 0 | 0 | (14,117) | (14,070)
New grants (in shares) | 475 | 0 | 13,475 | 14,055
Forfeitures and cancellations (in shares) | (7) | 0 | (564) | 0
Expense recognized (in shares) | 0 | 0 | 0 | 0
End of period (in shares) | 41,252 | 42,458 | 41,252 | 42,458
Accrued Expense |  |  |  |
Beginning of period | $ 38.2 | $ 9.8 | $ 56.3 | $ 43.7
Shares paid | 0.0 | 0.0 | (34.6) | (27.7)
New grants | 0.0 | 0.0 | 0.0 | 0.0
Forfeitures and cancellations | (0.2) | 0.0 | 0.2 | 0.4
Expense recognized | 7.7 | 6.0 | 23.8 | (0.6)
End of period | $ 45.7 | $ 15.8 | $ 45.7 | $ 15.8
Performance Cycle 2018 to 2020 |  |  |  |
Accrued Expense |  |  |  |
Percentage of target payout - minimum actual |  |  | 200.00% |
Performance Cycle 2017 to 2019 |  |  |  |
Accrued Expense |  |  |  |
Percentage of target payout - minimum actual |  |  |  | 174.00%
Percentage of target payout - maximum actual |  |  |  | 180.00%

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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 total reduction to unamortized compensation cost for performance shares forfeited during the 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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