Stock Option Outstanding and Exercisable (Detail) (USD $)	12 Months Ended
Dec. 31, 2012
$ 0.00-$10.00 [Member]
Exercise Price Range [Abstract]
Range of Exercise Price, Lower Range	$ 0.00
Range of Exercise Price, Upper Range	$ 10.00
Number of Outstanding Options	27,853
Outstanding Options, Weighted Average Exercise Price	$ 10.00
Outstanding Options, Weighted Average Remaining Contractual Term	6 years 1 month 2 days
Number of Exercisable Options	27,853
Exercisable Options, Weighted Average Exercise Price	$ 10.00
Exercisable Options, Weighted Average Remaining Contractual Term	6 years 1 month 2 days
$10.00-$20.00 [Member]
Exercise Price Range [Abstract]
Range of Exercise Price, Lower Range	$ 10.00
Range of Exercise Price, Upper Range	$ 20.00
Number of Outstanding Options	15,892
Outstanding Options, Weighted Average Exercise Price	$ 18.06
Outstanding Options, Weighted Average Remaining Contractual Term	8 years 10 months 21 days
Number of Exercisable Options	2,726
Exercisable Options, Weighted Average Exercise Price	$ 15.30
Exercisable Options, Weighted Average Remaining Contractual Term	7 years 7 months 2 days
$20.00-$30.00 [Member]
Exercise Price Range [Abstract]
Range of Exercise Price, Lower Range	$ 20.00
Range of Exercise Price, Upper Range	$ 30.00
Number of Outstanding Options	227,154
Outstanding Options, Weighted Average Exercise Price	$ 27.28
Outstanding Options, Weighted Average Remaining Contractual Term	6 years 7 months 6 days
Number of Exercisable Options	90,397
Exercisable Options, Weighted Average Exercise Price	$ 27.00
Exercisable Options, Weighted Average Remaining Contractual Term	3 years 3 months 22 days
$30.00-$40.00 [Member]
Exercise Price Range [Abstract]
Range of Exercise Price, Lower Range	$ 30.00
Range of Exercise Price, Upper Range	$ 40.00
Number of Outstanding Options	49,673
Outstanding Options, Weighted Average Exercise Price	$ 39.12
Outstanding Options, Weighted Average Remaining Contractual Term	2 years 4 months 21 days
Number of Exercisable Options	47,965
Exercisable Options, Weighted Average Exercise Price	$ 39.28
Exercisable Options, Weighted Average Remaining Contractual Term	2 years 2 months 5 days
$40.00-$50.00 [Member]
Exercise Price Range [Abstract]
Range of Exercise Price, Lower Range	$ 40.00
Range of Exercise Price, Upper Range	$ 50.00
Number of Outstanding Options	20,464
Outstanding Options, Weighted Average Exercise Price	$ 48.50
Outstanding Options, Weighted Average Remaining Contractual Term	2 years 10 months 28 days
Number of Exercisable Options	20,464
Exercisable Options, Weighted Average Exercise Price	$ 48.50
Exercisable Options, Weighted Average Remaining Contractual Term	2 years 10 months 28 days
$50.00-$60.00 [Member]
Exercise Price Range [Abstract]
Range of Exercise Price, Lower Range	$ 50.00
Range of Exercise Price, Upper Range	$ 60.00
Number of Outstanding Options	12,937
Outstanding Options, Weighted Average Exercise Price	$ 51.40
Outstanding Options, Weighted Average Remaining Contractual Term	2 years 2 months 23 days
Number of Exercisable Options	12,937
Exercisable Options, Weighted Average Exercise Price	$ 51.40
Exercisable Options, Weighted Average Remaining Contractual Term	2 years 2 months 23 days
$60.00-$70.00 [Member]
Exercise Price Range [Abstract]
Range of Exercise Price, Lower Range	$ 60.00
Range of Exercise Price, Upper Range	$ 70.00
Number of Outstanding Options	3,219
Outstanding Options, Weighted Average Exercise Price	$ 66.60
Outstanding Options, Weighted Average Remaining Contractual Term	1 year 0 months 7 days
Number of Exercisable Options	3,219
Exercisable Options, Weighted Average Exercise Price	$ 66.60
Exercisable Options, Weighted Average Remaining Contractual Term	1 year 0 months 7 days
$70.00-$80.00 [Member]
Exercise Price Range [Abstract]
Range of Exercise Price, Lower Range	$ 70.00
Range of Exercise Price, Upper Range	$ 80.00
Number of Outstanding Options	12,808
Outstanding Options, Weighted Average Exercise Price	$ 70.90
Outstanding Options, Weighted Average Remaining Contractual Term	1 year 1 month 21 days
Number of Exercisable Options	12,808
Exercisable Options, Weighted Average Exercise Price	$ 70.90
Exercisable Options, Weighted Average Remaining Contractual Term	1 year 1 month 21 days

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

+ References

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- Definition

Weighted average remaining contractual term of exercisable 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 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

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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

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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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-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.

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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.

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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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