The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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

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

-Publisher FASB

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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

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- Definition

The number of shares reserved for issuance under stock option agreements awarded under the plan that validly exist and are outstanding as of the balance sheet date, including vested options.

+ 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)(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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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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)

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

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- Definition

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

+ References

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Stock-Based Compensation - Additional Information Regarding Options Outstanding and Exercisable (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, Shares	2,831	3,608	3,786	4,196
Outstanding, Weighted Average Contractual Life (in years)	4 years 1 month 6 days
Outstanding, Weighted Average Exercise Price	$ 34.06	$ 28.06	$ 24.78	$ 21.77
Exercisable, Shares	1,305
Exercisable, Weighted Average Exercise Price	$ 27.66
$0.00 - $5.25 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, Shares	1
Outstanding, Weighted Average Contractual Life (in years)	3 months 18 days
Outstanding, Weighted Average Exercise Price	$ 1.32
Exercisable, Shares	1
Exercisable, Weighted Average Exercise Price	$ 1.32
$5.26 - $10.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, Shares	19
Outstanding, Weighted Average Contractual Life (in years)	2 years 1 month 6 days
Outstanding, Weighted Average Exercise Price	$ 8.56
Exercisable, Shares	19
Exercisable, Weighted Average Exercise Price	$ 8.56
$10.51 - $21.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, Shares	717
Outstanding, Weighted Average Contractual Life (in years)	3 years 2 months 12 days
Outstanding, Weighted Average Exercise Price	$ 19.53
Exercisable, Shares	479
Exercisable, Weighted Average Exercise Price	$ 19.46
$21.01 - $31.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, Shares	230
Outstanding, Weighted Average Contractual Life (in years)	2 years 6 months
Outstanding, Weighted Average Exercise Price	$ 28.14
Exercisable, Shares	209
Exercisable, Weighted Average Exercise Price	$ 28.11
$31.51 - $47.25 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, Shares	1,258
Outstanding, Weighted Average Contractual Life (in years)	4 years
Outstanding, Weighted Average Exercise Price	$ 37.30
Exercisable, Shares	597
Exercisable, Weighted Average Exercise Price	$ 34.70
$47.26 - $52.50 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Outstanding, Shares	606
Outstanding, Weighted Average Contractual Life (in years)	6 years 2 months 12 days
Outstanding, Weighted Average Exercise Price	$ 47.58