Stock Plans (Narrative) (Details) (USD $)	12 Months Ended
Dec. 31, 2011 years	Dec. 31, 2010	Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of tranches in which restricted stock is vested	3
Restricted stock for management retention awards with various vesting periods, years	four, five and six years
Shares reserved for future grants	355,002	236,489
Stock-based compensation expense capitalized	$ 0	$ 0	$ 0
Cash proceeds from exercise of options	1,316,000	7,809,000	255,000
Excess tax benefit (provision) related to stock plans	632,000	3,462,000	(386,000)
Number of years historical volatility using daily stock prices over which expected volatility is based	10
Aggregate intrinsic value of stock options exercisable	0
Aggregate intrinsic value of stock options outstanding	4,000,000
Total intrinsic value of stock options exercised	1,800,000	10,900,000	400,000
Fair value of restricted stock vested	3,400,000	1,200,000	700,000
Unrecognized stock-based compensation expense	6,300,000
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized, in years	1
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target award based on achieving targeted performance conditions	0.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of target award based on achieving targeted performance conditions	200.00%
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options expiration period	ten years
Options exercisable period	three years
Excess tax benefit (provision) related to stock plans	$ 700,000	$ 4,300,000	$ 100,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options exercisable period	three years

Number of years historical volatility using daily stock prices over which expected volatility is based.

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Percentage of target award based on achieving a targeted return on net assets based on which final number of shares to be issued for performance stock units.

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- Definition

Share-based compensation arrangement by share-based payment award, award with various vesting periods.

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Share based compensation arrangement by share based payment award number of tranches in which restricted stock is vested.

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- Definition

Share based compensation arrangement by share based payment award options exercisable period.

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- Definition

Stock-based compensation expense capitalized.

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- Definition

Stock Options Expiration Period

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- Definition

Aggregate number of common shares reserved for future issuance.

+ References

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 4

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-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.29)

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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.

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The weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, using a decimal to express in number of years.

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- Definition

Reductions in the entity's income taxes that arise when compensation cost (from non-qualified share-based compensation) recognized on the entity's tax return exceeds compensation cost from equity-based compensation recognized in financial statements. This element represents the cash inflow reported in the enterprise's financing activities.

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-Topic 718

-SubTopic 20

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- Definition

The cash inflow associated with the amount received from holders exercising their stock options. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Financing Activities

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-Name Accounting Standards Codification

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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.

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- Definition

The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of vested portions of options outstanding and currently exercisable under the option plan as of the balance sheet date.

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The total accumulated difference between fair values of underlying shares on dates of exercise and exercise price on options which were exercised (or share units converted) into shares during the reporting period under the plan.

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The total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices pertaining to options outstanding under the plan as of the balance sheet date.

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