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Deferred Compensation - Additional Information (Detail) - USD ($) shares in Millions, $ in Millions | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 30, 2020 | Mar. 31, 2020 | Jun. 30, 2019 | Mar. 31, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Dec. 31, 2019
Investments And Employee Deferred Compensation Plan [Line Items] |  |  |  |  |  |  |
Deferred Equity Participation Plan, distributions to key executives, age |  |  |  |  | age 62 (or the one-year anniversary of the date of the grant for participants over the age of 61 as of the grant date) or upon or after their actual retirement. |  |
Deferred Equity Participation Sub-plans, distributions requisite service description |  |  |  |  | we annually make awards under sub-plans of the DEPP for certain production staff, which generally provide for vesting and/or distributions no sooner than five years from the date of awards, although certain awards vest and/or distribute after the earlier of fifteen years or the participant reaching age 65. |  |
Deferred Equity Participation Sub-plans, distributions to key executives, age |  |  |  |  | age 65 |  |
Deferred Equity Participation Plan (DEPP) [Member] |  |  |  |  |  |  |
Investments And Employee Deferred Compensation Plan [Line Items] |  |  |  |  |  |  |
Awards approved by committee, value |  | $ 14.1 |  | $ 10.1 |  |  |
Charge to compensation expenses related to awards | $ 3.7 |  | $ 2.6 |  | $ 6.0 | $ 4.6 |
Unearned deferred compensation, value |  |  |  |  | $ 70.7 |  | $ 64.5
Unearned deferred compensation, shares |  |  |  |  | 2.9 |  | 2.9
Total intrinsic value of unvested equity based awards |  |  |  |  | $ 283.8 |  | $ 276.3
Cash and equity awards with aggregate fair value vested and distributed to participants |  |  |  |  | 9.8 | 1.3 |
Deferred Equity Participation Plan Sub Plans [Member] |  |  |  |  |  |  |
Investments And Employee Deferred Compensation Plan [Line Items] |  |  |  |  |  |  |
Awards approved by committee, value |  | 1.8 |  | 2.6 |  |  |
Charge to compensation expenses related to awards | 0.7 |  | 0.7 |  | 1.4 | 1.2 |
Distributions from the sub-plans |  |  |  |  | 0.0 | 0.0 |
Deferred Cash Participation Plan (DCPP) [Member] |  |  |  |  |  |  |
Investments And Employee Deferred Compensation Plan [Line Items] |  |  |  |  |  |  |
Awards approved by committee, value |  | $ 3.0 |  | $ 2.4 |  |  |
Charge to compensation expenses related to awards | $ 1.7 |  | $ 1.2 |  | 3.4 | 2.3 |
Cash and equity awards with aggregate fair value vested and distributed to participants |  |  |  |  | $ 7.3 | $ 2.5 |

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- Definition Deferred Equity Participation Plan, Distributions to Key Executives, Age + References No definition available. + Details
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- Definition Deferred equity participation sub plan distributions requisite service description. + References No definition available. + Details
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