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Schedule of Asset Allocation (Detail) - United States	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	100.00%
Actual asset allocations	100.00%	100.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocations	2.00%
Debt Securities
Defined Benefit Plan Disclosure [Line Items]
Target asset allocation	100.00%
Actual asset allocations	91.00%	98.00%
Cash and Other
Defined Benefit Plan Disclosure [Line Items]
Actual asset allocations	7.00%	2.00%

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Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=112275985&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=108410482&loc=d3e1928-114920

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Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

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-Name Accounting Standards Codification
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