Stock Options by Range of Exercise Prices (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2010 Year Entity Contract Location
Options Outstanding Shares	1.4
Options Outstanding Weighted Average Remaining Life	8
Options Outstanding, Weighted Average Exercise Price	$ 7.50
Options Exercisable, Shares	0.9
Options Exercisable, Weighted Average Exercise Price	$ 7.14
Range 1
Range of Exercise Prices Lower Limit	$ 4
Range of Exercise Prices Upper Limit	$ 6
Options Outstanding Shares	0.3
Options Outstanding Weighted Average Remaining Life	8
Options Outstanding, Weighted Average Exercise Price	$ 5.08
Options Exercisable, Shares	0.3
Options Exercisable, Weighted Average Exercise Price	$ 5.08
Range 2
Range of Exercise Prices Lower Limit	$ 7
Range of Exercise Prices Upper Limit	$ 9
Options Outstanding Shares	1.0
Options Outstanding Weighted Average Remaining Life	8
Options Outstanding, Weighted Average Exercise Price	$ 8.01
Options Exercisable, Shares	0.5
Options Exercisable, Weighted Average Exercise Price	$ 7.99
Range 3
Range of Exercise Prices Lower Limit	$ 10
Range of Exercise Prices Upper Limit	$ 12
Options Outstanding Shares	0.1
Options Outstanding Weighted Average Remaining Life	9
Options Outstanding, Weighted Average Exercise Price	$ 11.02
Options Exercisable, Shares	0.1
Options Exercisable, Weighted Average Exercise Price	$ 10.88

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 Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph b(1)(c), d(2)

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- Definition

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 Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph b(1)(c)

+ Details

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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)(a)

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)(b)

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- Definition

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.

+ 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)(a)

+ Details

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph A240
-Subparagraph a

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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

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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 Statement of Financial Accounting Standard (FAS)
-Number 123R
-Paragraph 64

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