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Shared-Based Compensation - Summary of Number of Awards Granted and Grand Date Fair Value (Detail) shares in Thousands	3 Months Ended
	Mar. 31, 2018 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grant Date Fair Value	$ 24.55
TSR Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted in fair values, Shares | shares	55
Grant Date Fair Value	$ 24.65
ROIC Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of awards granted in fair values, Shares | shares	55
Grant Date Fair Value	$ 24.55

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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- Definition

Number of equity instruments other than options outstanding, including both vested and non-vested instruments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

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