Expiration Date

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- Definition

Increase decrease in excess tax benefits realized net.

+ References

No definition available.

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- Definition

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

+ References

No definition available.

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Description

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- Definition

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

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No definition available.

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- Definition

Share Based Compensation Arrangement By Share Based Payment Award, Options, Vesting Period

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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.29)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

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-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

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (i)

-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 h

-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

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.

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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.

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- Definition

The total fair value of equity-based awards for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

+ 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 (d)(2)

-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 c(2)

-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 difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

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

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- Definition

Purchase price of common stock expressed as a percentage of its fair market value.

+ References

No definition available.

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Share-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Capitalized share-based compensation cost	$ 0	$ 0	$ 0
Increase (decrease) in net excess tax benefits realized	1.7	0.9	0.1
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price percentage of stock at fair market value	85.00%
Employee Stock Purchase Plan \| Maximum New Limit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of company common stock available for issuance	289,133
Board Dsus Granted To Nonemployee Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to grants	0.9
Weighted-average period for which cost is expected to be recognized, (in years)	1 year
Total fair value of share awards vested	0.9	0.7	0.2
Dsu Performance Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to grants	0.1
Share-based compensation options awarded, number of installments	4
Total fair value of share awards vested	0.4	0.2	0
Maximum percentage to return on invested capital for annual performance period	12.00%
DSU Service Award
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total fair value of share awards vested	0.6	0.7	0
Share-based compensation awarded, vesting period	4 years
Performance Award Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to grants	1.4
Weighted-average period for which cost is expected to be recognized, (in years)	2 years 6 months
Share-based compensation options awarded, number of installments	4
Total fair value of share awards vested	1.1	0.8
Maximum percentage to return on invested capital for annual performance period	12.00%
Service Award Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to grants	3.7
Weighted-average period for which cost is expected to be recognized, (in years)	2 years 10 months 24 days
Share-based compensation options awarded, number of installments	4
Total fair value of share awards vested	2.1	2.6	2.3
Service Award Units \| Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost related to grants	0.1
Weighted-average period for which cost is expected to be recognized, (in 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	Stock options awarded to employees under the SIPs generally vest annually over a three-year period
Stock options term in years	10 years
Total unrecognized compensation cost related to grants	$ 2.9
Weighted-average period for which cost is expected to be recognized, (in years)	2 years 1 month 6 days
2008 Equity Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future grants	2,561,106
Expiration Date	May 25, 2020
One Executive
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation options awarded, number of installments	12