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Retirement Plans - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items] |  |  |
Expected period of return on plan assets, years | 10 years | 10 years |
Minimum contribution by employer | $ 0.0 | $ 0.0 | $ 0.0
Discretionary contributions by employer | 0.0 | 30.0 | 0.0
Fair value of plan assets | 243.7 | 220.0 | 219.4
Postretirement benefit obligation and unfunded status of plan | 274.4 | 253.2 | 271.4
Net periodic postretirement benefit cost | $ 3.6 | (1.0) | 2.7
Foreign Retirement Plans [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Percentage of eligible compensation for matching contributions by employer | 5.00% |  |
Contribution expense to plan | $ 39.8 | 34.9 | 32.0
Matching contributions by employer, percentage | 100.00% |  |
Additional percentage of eligible compensation for matching contributions by employer | 5.00% |  |
Qualified Contributory Savings and Thrift 401(k) Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Percentage of eligible compensation for matching contributions by employer | 5.00% |  |
Contribution expense to plan | $ 59.4 | 53.9 | 51.6
Matching contributions by employer, percentage | 100.00% |  |
Matching contributions vesting schedule | 5 years |  |
Nonqualified Deferred Compensation Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Percentage of eligible compensation for matching contributions by employer | 5.00% |  |
Contribution expense to plan | $ 7.1 | 6.5 | 6.4
Fair value of plan assets | 452.9 | 355.0 |
Retiree Health Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Postretirement benefit obligation and unfunded status of plan | 1.7 | 2.0 |
Net periodic postretirement benefit cost | $ 0.4 | $ 0.3 | $ 0.3

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