Options Outstanding and Exercisable (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011 Year
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Options outstanding shares	9,357
Options outstanding weighted-average remaining contractual life	4.12
Options outstanding weighted-average exercise price	$ 36.71
Options exercisable shares	7,913
Options exercisable shares weighted-average exercise price	$ 37.75
Range 1
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per-share exercise prices, lower limit	$ 25.00
Range of per-share exercise prices, upper limit	$ 29.99
Options outstanding shares	1,615
Options outstanding weighted-average remaining contractual life	7.35
Options outstanding weighted-average exercise price	$ 26.59
Options exercisable shares	1,045
Options exercisable shares weighted-average exercise price	$ 26.58
Range 2
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per-share exercise prices, lower limit	$ 30.00
Range of per-share exercise prices, upper limit	$ 34.99
Options outstanding shares	2,847
Options outstanding weighted-average remaining contractual life	3.22
Options outstanding weighted-average exercise price	$ 33.76
Options exercisable shares	1,973
Options exercisable shares weighted-average exercise price	$ 33.67
Range 3
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per-share exercise prices, lower limit	$ 35.00
Range of per-share exercise prices, upper limit	$ 39.99
Options outstanding shares	1,880
Options outstanding weighted-average remaining contractual life	3.46
Options outstanding weighted-average exercise price	$ 38.79
Options exercisable shares	1,880
Options exercisable shares weighted-average exercise price	$ 38.79
Range 4
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per-share exercise prices, lower limit	$ 40.00
Range of per-share exercise prices, upper limit	$ 44.99
Options outstanding shares	1,813
Options outstanding weighted-average remaining contractual life	3.49
Options outstanding weighted-average exercise price	$ 42.56
Options exercisable shares	1,813
Options exercisable shares weighted-average exercise price	$ 42.56
Range 5
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of per-share exercise prices, lower limit	$ 45.00
Range of per-share exercise prices, upper limit	$ 49.99
Options outstanding shares	1,202
Options outstanding weighted-average remaining contractual life	3.88
Options outstanding weighted-average exercise price	$ 45.26
Options exercisable shares	1,202
Options exercisable shares weighted-average exercise price	$ 45.26

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.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

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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.

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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.

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The weighted average price as of the beginning of the year at which grantees can acquire the shares reserved for issuance under the stock option plan.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

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-Subparagraph b(1)(a)

-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 period between the balance sheet date and expiration for all awards outstanding under the plan, which may be expressed in a decimal value for number of years.

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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.

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