Equity - Additional Information About Stock Options Outstanding (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Shares Underlying Options, Options Outstanding	1,958,633
Weighted Average Remaining Life (Years), Options Outstanding	4 years 1 month 17 days
Weighted Average Exercise Price, Options Outstanding	$ 28.43
Number Exercisable, Options Exercisable	1,846,465
Weighted Average Exercise Price, Options Exercisable	$ 28.35
$20.49 to $21.99 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Option Plans Exercise Price, lower range limit	$ 20.49
Stock Option Plans Exercise Price, upper range limit	$ 21.99
Number of Shares Underlying Options, Options Outstanding	513,103
Weighted Average Remaining Life (Years), Options Outstanding	2 years 3 months
Weighted Average Exercise Price, Options Outstanding	$ 21.24
Number Exercisable, Options Exercisable	513,103
Weighted Average Exercise Price, Options Exercisable	$ 21.24
$22.00 to $29.74 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Option Plans Exercise Price, lower range limit	$ 22.00
Stock Option Plans Exercise Price, upper range limit	$ 29.74
Number of Shares Underlying Options, Options Outstanding	312,531
Weighted Average Remaining Life (Years), Options Outstanding	2 years 8 months 16 days
Weighted Average Exercise Price, Options Outstanding	$ 27.13
Number Exercisable, Options Exercisable	294,553
Weighted Average Exercise Price, Options Exercisable	$ 27.24
$ 29.75 to $35.73 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Stock Option Plans Exercise Price, lower range limit	$ 29.75
Stock Option Plans Exercise Price, upper range limit	$ 35.73
Number of Shares Underlying Options, Options Outstanding	1,132,999
Weighted Average Remaining Life (Years), Options Outstanding	5 years 4 months 13 days
Weighted Average Exercise Price, Options Outstanding	$ 32.04
Number Exercisable, Options Exercisable	1,038,809
Weighted Average Exercise Price, Options Exercisable	$ 32.17

Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding.

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)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ 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 (g)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

+ 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)(iii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices.

+ 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)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices.

+ 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)-(ii)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

Weighted average remaining contractual term of outstanding stock options, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ 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 (e)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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- Definition

The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range.

+ 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 (g)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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