Maximum percentage to return on invested capital for annual performance period.

No definition available.

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- Definition

Share-based Compensation Arrangement By Share-based Payment Award, Award Vesting, Number Of Installments

+ References

No definition available.

+ Details

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Stock Options Contractual Period

+ References

No definition available.

+ Details

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- Definition

Represents the compensation cost capitalized during the period arising from equity-based compensation arrangements (for example, shares of stock, units, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph g(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 (h)(1)(ii)

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

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- Definition

As of the balance sheet date, the aggregate unrecognized cost of equity-based awards made to employees under equity-based compensation awards that have yet to vest.

+ References

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- Definition

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

+ Details

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Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target 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

-Subparagraph (c)(2)(iii)(1)

-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 c(1)

-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 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph A240

-Subparagraph b(2)(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.

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Period Type:	duration

- Definition

Net number of share options (or share units) granted during the period.

+ References

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	duration

- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	instant

- 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

+ Details

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- Definition

Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded.

+ References

No definition available.

+ Details

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Share-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized share-based compensation cost			$ 0	$ 0
Number of stock options granted	12,511	0	106,466	73,225
Weighted-average exercise price for stock options granted	$ 35.46		$ 34.06	$ 44.06
Weighted-average exercise price for outstanding stock options	$ 34.95		$ 34.95
Weighted-average remaining contractual term for outstanding stock options			5 years 4 months 24 days
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation options awarded, vesting period			3 years
Stock options term (in years)			10
Unrecognized compensation cost	2.5		2.5
Weighted-average period for which cost is expected to be recognized, in years			2 years 1 month 6 days
Service Award Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	1.4		1.4
Weighted-average period for which cost is expected to be recognized, in years			1 year 9 months 18 days
Number of shares granted during the period	4,583		4,583	18,434
Weighted average grant-date fair value per share granted during the period	$ 35.46		$ 35.46	$ 42.72
Performance Award Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	2.1		2.1
Weighted-average period for which cost is expected to be recognized, in years			2 years 10 months 24 days
Number of shares granted during the period			34,229	22,511
Weighted average grant-date fair value per share granted during the period			$ 33.87	$ 44.44
Maximum percentage to return on invested capital for annual performance period			12.00%
Share-based compensation options awarded, number of installments			4
Board Dsus Granted To Nonemployee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	1.5		1.5
Weighted-average period for which cost is expected to be recognized, in years			1 year 3 months 18 days
Board DSUs And Dividend Equivalents Granted To Board
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation options awarded, vesting period			3 years
Number of shares granted during the period	21,179	21,061	22,568	22,481
Weighted average grant-date fair value per share granted during the period	$ 35.41	40.67	$ 35.49	$ 40.60
Share-based compensation options awarded, number of installments			3
Chief Executive Officer \| DSU Service Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation options awarded, vesting period			4 years
Number of shares granted during the period			1,181	900
Weighted average grant-date fair value per share granted during the period			$ 33.87	$ 44.44
Chief Executive Officer \| Dsu Performance Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	1.4		1.4
Weighted-average period for which cost is expected to be recognized, in years			6 months
Number of shares granted during the period			59,049	24,122
Weighted average grant-date fair value per share granted during the period			$ 33.87	$ 44.44
Maximum percentage to return on invested capital for annual performance period			12.00%
Share-based compensation options awarded, number of installments			4
Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares granted during the period	5,640		5,640
Weighted average grant-date fair value per share granted during the period	$ 35.46		$ 35.46
Board of Directors \| Service Award Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost	$ 0.2		$ 0.2
Weighted-average period for which cost is expected to be recognized, in years			10 months 24 days