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Employee Benefit Plans (Deferred Compensation Plans) - Fair Value of Assets Held by Trust and Amounts Payable to Plan Participants (Detail) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016
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Defined Benefit Plan Disclosure [Line Items] |  |
Long-term Investments | $ 118,038 | $ 190,723
Long-term Investments | 19,883 | 14,596
Amounts Payable to Plan Participants Non-current Liabilities | 19,883 | 14,596
Deferred Compensation Plan Assets [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Long-term Investments | 19,883 | 14,596
Non-Current Liabilities [Member] |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Amounts Payable to Plan Participants Non-current Liabilities | $ 19,883 | $ 14,596

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- Definition Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 5 -Subparagraph (aa) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562 + Details
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- Definition Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements payable beyond one year (or the operating cycle, if longer). + References No definition available. + Details
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- Definition Carrying amount as of the balance sheet date of assets held under deferred compensation agreements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.17) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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