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Pension and Savings Plans Textuals (Details) | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Apr. 01, 2017 USD ($) years plan | Dec. 31, 2017 USD ($) | Dec. 31, 2020 | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Defined Contribution Plans [Abstract] |  |  |  |  |
Number of 401(k) plans | plan | 2 |  |  |  |
Paid discretionary contributions to defined contribution pension plans, company match | $ 5,500,000 | $ 25,500,000 |  | $ 27,800,000 | $ 30,300,000
Discretionary contributions to defined contribution pension plans, granted |  |  |  | 0 |
Payment of prior performance contributions |  | 0 |  | $ 8,900,000 | $ 8,500,000
Additional discretionary contributions to defined contribution pension plans, performance feature | $ 0 | $ 0 |  |  |
Pension Plan |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Retirees Affected by Pension Settlement |  | 1,950 |  |  |
Percentage of company's qualified pension plans on a GAAP accounting basis |  |  |  | 80.00% |
Expected long-term return on plan assets | 5.90% | 5.90% |  | 4.20% | 5.65%
Percentage of actuarial gains and losses amortized | 5.00% |  |  |  |
Defined Benefit Plan, Amortization Period | years | 5 |  |  |  |
Defined Benefit Plan, Accumulated Benefit Obligation |  |  |  | $ 853,800,000 | $ 795,900,000
Defined Contribution Plans [Abstract] |  |  |  |  |
Additional discretionary contributions to defined contribution pension plans, performance feature |  |  |  | 20,000,000.0 |
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement |  | $ 71,400,000 |  |  |
Pension obligations | $ 0 | 2,100,000 |  | $ 0 | $ 0
Fixed Income Investments |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage |  |  |  | 100.00% |
Real Estate |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage |  |  |  | 1.00% | 1.00%
Scenario, Forecast | Pension Plan |  |  |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |  |  |
Expected long-term return on plan assets |  |  | 3.60% |  |
Australia |  |  |  |  |
Defined Contribution Plans [Abstract] |  |  |  |  |
Paid discretionary contributions to defined contribution pension plans, company match | 6,100,000 | $ 19,900,000 |  | $ 26,500,000 | $ 31,600,000
Payment of prior performance contributions |  |  |  | $ 3,000,000 |
Additional discretionary contributions to defined contribution pension plans, performance feature | $ 0 |  |  |  | $ 3,000,000

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