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Debt and Lease Commitments (Parenthetical) (Detail)		12 Months Ended
	Jan. 15, 2015	Dec. 31, 2017	Dec. 31, 2016
Bank Credit Lines
Debt Instrument [Line Items]
Line of credit facility, average year-end interest rate		2.50%	2.40%
Commercial Paper
Debt Instrument [Line Items]
Line of credit facility, average year-end interest rate		1.70%	1.10%
Term Notes With Insurance Companies
Debt Instrument [Line Items]
Line of credit facility, average year-end interest rate		3.40%	3.50%
Debt instrument maturity	2030	2029	2034
Canadian Term Notes With Insurance Companies
Debt Instrument [Line Items]
Line of credit facility, average year-end interest rate		5.30%	5.30%
Debt instrument maturity		2018	2018
Revolving Credit Agreement Borrowings
Debt Instrument [Line Items]
Line of credit facility, average year-end interest rate		2.50%	1.70%

X

- Definition

Debt Instrument Maturity Date Year

+ References

No definition available.

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X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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X

- Definition

The effective interest rate at the end of the reporting period.

+ 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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