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Earnings Per Share - Additional Information (Detail) - $ / shares shares in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Equity Unit Purchase Agreements [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Number of anti-dilutive securities	3	8
Stock Options [Member]
Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average exercise price of options	$ 33.33	$ 38.16

X

- Definition

Dilutive Securities Included And Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]

+ References

No definition available.

+ Details

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- Definition

The weighted average exercise price of stock options whose individual exercise prices were greater than the average market price of an entity's common stock during the period.

+ References

No definition available.

+ Details

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- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

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