Stock Options Outstanding (Detail) (USD $)	12 Months Ended
Dec. 31, 2012
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding Options, Shares	2,060,413
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	3 years 11 months 1 day
Outstanding Options, Weighted Average Exercise Price	$ 49.15
Exercisable Options, Shares	1,091,812
Exercisable Options, Weighted Average Exercise Price	$ 44.50
$15.35 - $27.83
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 15.35
Range of Exercise Prices, maximum	$ 27.83
Outstanding Options, Shares	227,557
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	3 years 3 months 26 days
Outstanding Options, Weighted Average Exercise Price	$ 19.61
Exercisable Options, Shares	148,303
Exercisable Options, Weighted Average Exercise Price	$ 19.59
$27.84 - $45.23
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 27.84
Range of Exercise Prices, maximum	$ 45.23
Outstanding Options, Shares	266,237
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	3 years 11 months 19 days
Outstanding Options, Weighted Average Exercise Price	$ 37.62
Exercisable Options, Shares	163,882
Exercisable Options, Weighted Average Exercise Price	$ 36.47
$45.24 - $48.63
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 45.24
Range of Exercise Prices, maximum	$ 48.63
Outstanding Options, Shares	140,522
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	1 year 8 months 12 days
Outstanding Options, Weighted Average Exercise Price	$ 47.85
Exercisable Options, Shares	128,278
Exercisable Options, Weighted Average Exercise Price	$ 47.93
$48.64 - $48.80
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 48.64
Range of Exercise Prices, maximum	$ 48.80
Outstanding Options, Shares	241,392
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	2 years 3 months 26 days
Outstanding Options, Weighted Average Exercise Price	$ 48.76
Exercisable Options, Shares	241,392
Exercisable Options, Weighted Average Exercise Price	$ 48.76
$48.81 - $49.69
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 48.81
Range of Exercise Prices, maximum	$ 49.69
Outstanding Options, Shares	234,837
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	4 years 3 months 11 days
Outstanding Options, Weighted Average Exercise Price	$ 49.18
Exercisable Options, Shares	107,823
Exercisable Options, Weighted Average Exercise Price	$ 49.19
$49.70 - $55.87
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 49.70
Range of Exercise Prices, maximum	$ 55.87
Outstanding Options, Shares	237,117
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	1 year 3 months 29 days
Outstanding Options, Weighted Average Exercise Price	$ 52.28
Exercisable Options, Shares	212,176
Exercisable Options, Weighted Average Exercise Price	$ 52.21
$55.88 - $60.46
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 55.88
Range of Exercise Prices, maximum	$ 60.46
Outstanding Options, Shares	350,813
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	5 years 3 months 22 days
Outstanding Options, Weighted Average Exercise Price	$ 60.05
Exercisable Options, Shares	89,419
Exercisable Options, Weighted Average Exercise Price	$ 60.02
$60.47 - $63.62
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 60.47
Range of Exercise Prices, maximum	$ 63.62
Outstanding Options, Shares	11,920
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	6 years 2 months 12 days
Outstanding Options, Weighted Average Exercise Price	$ 62.46
Exercisable Options, Shares	539
Exercisable Options, Weighted Average Exercise Price	$ 60.62
$63.63 - $64.43
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices, minimum	$ 63.63
Range of Exercise Prices, maximum	$ 64.43
Outstanding Options, Shares	350,018
Outstanding Options ,Weighted Average Remaining Contractual Life in Years	6 years 3 months 29 days
Outstanding Options, Weighted Average Exercise Price	$ 64.37
Exercisable Options, Shares	0
Exercisable Options, Weighted Average Exercise Price	$ 0.00

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

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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 Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: 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

+ Details

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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 Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(c)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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)(iii)

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

+ Details

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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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(1)(a, b)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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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

+ Details

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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

+ Details

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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

+ Details

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