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Pension Plans - Additional Information (Detail) - USD ($) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Pension And Other Employee Benefit Plans [Line Items] |  |  |
Estimated net loss for the PLP-USA pension plan in 2018 | $ 200,000 |  |
Prior service cost | 0 |  |
Pre-tax unfunded pension obligation gain (loss) | $ (700,000) |  |
Discount rate | 3.75% | 4.25% |
Asset performance rate of return assumption | 8.00% |  |
Expected long-term return on plan assets | 8.00% | 8.00% | 8.00%
Contribution to pension plan | $ 0 |  |
Expense for contribution plan | $ 5,100,000 | $ 5,800,000 | $ 5,500,000
Weighted average of one year treasury bill | 1.00% |  |
Interest rate for the supplemental profit sharing plan | 2.76% | 1.65% |
Expense for the supplemental profit sharing plan | $ 500,000 | $ 500,000 | $ 300,000
Supplemental profit sharing plan unfunded status | 4,800,000 | $ 4,300,000 |
Reduction in Discount Rate [Member] |  |  |
Pension And Other Employee Benefit Plans [Line Items] |  |  |
Pre-tax unfunded pension obligation gain (loss) | $ (2,800,000) |  |
Discount rate | 0.50% |  |
Gain on Industry Updates to Mortality Table [Member] |  |  |
Pension And Other Employee Benefit Plans [Line Items] |  |  |
Pre-tax unfunded pension obligation gain (loss) | $ 300,000 |  |
Demographic Changes [Member] |  |  |
Pension And Other Employee Benefit Plans [Line Items] |  |  |
Pre-tax unfunded pension obligation gain (loss) | 200,000 |  |
Asset Performance [Member] |  |  |
Pension And Other Employee Benefit Plans [Line Items] |  |  |
Pre-tax unfunded pension obligation gain (loss) | $ 1,600,000 |  |

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- Definition Defined benefit plan unfunded status of plan. + References No definition available. + Details
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- Definition Pension and other employee benefit plans. + References No definition available. + Details
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- Definition Retirement and profit sharing plan expenses. + References No definition available. + Details
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- Definition Supplemental profit sharing plan interest rate. + References No definition available. + Details
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- Definition Supplemental profit sharing plan variable rate basis. + References No definition available. + Details
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- Definition Amount, before tax, after reclassification adjustment, of increase (decrease) in accumulated other comprehensive income from gain (loss) of 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 (i) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e637-108580 + Details
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- Definition Weighted average rate for present value of future retirement benefits cash flows, used to determine benefit obligation of 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 (k)(1) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of 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 (k)(3) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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- Definition Amount included in accumulated other comprehensive (income) loss for prior service cost (credit) expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position. + 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 (s) -URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920 + Details
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