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Retirement Plans - Additional Information (Detail) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
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
Discretionary contributions by employer | 0 | 0 | 0
Fair value of plan assets | 219,400,000 | 207,800,000 | 207,500,000
Postretirement benefit obligation and unfunded status of plan | 271,400,000 | 261,300,000 | 261,800,000
Net periodic postretirement benefit cost | $ 2,700,000 | 3,000,000 | 2,800,000
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 | $ 32,000,000 | 30,600,000 | 31,700,000
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 | $ 51,600,000 | 47,700,000 | 42,500,000
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 | $ 6,400,000 | 5,800,000 | 4,700,000
Fair value of plan assets | 329,000,000 | 263,300,000 |
Retiree Health Plan [Member] |  |  |
Defined Benefit Plan Disclosure [Line Items] |  |  |
Postretirement benefit obligation and unfunded status of plan | 2,500,000 | 2,700,000 |
Net periodic postretirement benefit cost | $ (300,000) | $ (300,000) | $ (300,000)

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- Definition Defined benefit plan, percentage of eligible compensation for matching contributions by employer + References No definition available. + Details
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- Definition Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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