Share-Based Compensation - Schedule of Weighted Average Remaining Life of Options Outstanding within Stated Exercise Prices (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range Per Share, Options Outstanding, Number of Options	867,682
Exercise Price Range Per Share, Options Outstanding, Weighted Average Exercise Price	$ 55.92
Exercise Price Range Per Share, Options Outstanding, Weighted Average Remaining Life	5 years 1 month 6 days
Exercise Price Range Per Share, Options Exercisable, Number of Options	562,752
Exercise Price Range Per Share, Options Exercisable, Weighted Average Exercise Price	$ 55.92
Exercise Price Range Per Share From 34.33 to 51.69 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range Per Share, Options Outstanding, Number of Options	182,416
Exercise Price Range Per Share, Options Outstanding, Weighted Average Exercise Price	$ 49.24
Exercise Price Range Per Share, Options Outstanding, Weighted Average Remaining Life	4 years 3 months 18 days
Exercise Price Range Per Share, Options Exercisable, Number of Options	118,312
Exercise Price Range Per Share, Options Exercisable, Weighted Average Exercise Price	$ 48.53
Exercise Price Range Per Share, Minimum	$ 34.33
Exercise Price Range Per Share, Maximum	$ 51.69
Exercise Price Range Per Share From 51.70 to 52.35 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range Per Share, Options Outstanding, Number of Options	111,197
Exercise Price Range Per Share, Options Outstanding, Weighted Average Exercise Price	$ 52.33
Exercise Price Range Per Share, Options Outstanding, Weighted Average Remaining Life	7 years 1 month
Exercise Price Range Per Share, Options Exercisable, Number of Options	43,156
Exercise Price Range Per Share, Options Exercisable, Weighted Average Exercise Price	$ 52.33
Exercise Price Range Per Share, Minimum	$ 51.70
Exercise Price Range Per Share, Maximum	$ 52.35
Exercise Price Range Per Share From 52.36 to 54.68 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range Per Share, Options Outstanding, Number of Options	146,995
Exercise Price Range Per Share, Options Outstanding, Weighted Average Exercise Price	$ 53.43
Exercise Price Range Per Share, Options Outstanding, Weighted Average Remaining Life	6 years 6 months
Exercise Price Range Per Share, Options Exercisable, Number of Options	90,146
Exercise Price Range Per Share, Options Exercisable, Weighted Average Exercise Price	$ 54.10
Exercise Price Range Per Share, Minimum	$ 52.36
Exercise Price Range Per Share, Maximum	$ 54.68
Exercise Price Range Per Share From 54.69 to 57.60 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range Per Share, Options Outstanding, Number of Options	142,360
Exercise Price Range Per Share, Options Outstanding, Weighted Average Exercise Price	$ 56.52
Exercise Price Range Per Share, Options Outstanding, Weighted Average Remaining Life	3 years 8 months 12 days
Exercise Price Range Per Share, Options Exercisable, Number of Options	120,873
Exercise Price Range Per Share, Options Exercisable, Weighted Average Exercise Price	$ 56.68
Exercise Price Range Per Share, Minimum	$ 54.69
Exercise Price Range Per Share, Maximum	$ 57.60
Exercise Price Range Per Share From 57.61 to 59.83 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range Per Share, Options Outstanding, Number of Options	105,666
Exercise Price Range Per Share, Options Outstanding, Weighted Average Exercise Price	$ 58.38
Exercise Price Range Per Share, Options Outstanding, Weighted Average Remaining Life	1 year 6 months
Exercise Price Range Per Share, Options Exercisable, Number of Options	105,666
Exercise Price Range Per Share, Options Exercisable, Weighted Average Exercise Price	$ 58.38
Exercise Price Range Per Share, Minimum	$ 57.61
Exercise Price Range Per Share, Maximum	$ 59.83
Exercise Price Range Per Share From 59.84 to 111.71 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercise Price Range Per Share, Options Outstanding, Number of Options	179,048
Exercise Price Range Per Share, Options Outstanding, Weighted Average Exercise Price	$ 65.06
Exercise Price Range Per Share, Options Outstanding, Weighted Average Remaining Life	6 years 8 months 12 days
Exercise Price Range Per Share, Options Exercisable, Number of Options	84,599
Exercise Price Range Per Share, Options Exercisable, Weighted Average Exercise Price	$ 65.89
Exercise Price Range Per Share, Minimum	$ 59.84
Exercise Price Range Per Share, Maximum	$ 111.71

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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