Share-Based Compensation (Details) (USD $)	3 Months Ended
Mar. 31, 2012 Y	Mar. 31, 2011	Dec. 31, 2011
Share-Based Compensation (Textual) [Abstract]
Total compensation cost related to nonvested awards, unrecognized	$ 13,600,000		$ 15,900,000
Weighted-average period to recognize compensation cost (in years)	3
Aggregate intrinsic value for outstanding options and RSUs	98,800,000
Aggregate intrinsic value for vested options and RSUs	64,600,000
Weighted-average remaining contractual life for outstanding options and RSUs, in years	6
Weighted-average remaining contractual life for exercisable options and RSUs, in years	5
Share-based compensation	1,700,000	500,000
Excess tax Benefits (expense)	$ 5,335,000	$ 529,000
Outstanding options to purchase common shares not included in dilutive share	0	0
Share-based payment award granted minimum vesting period range	1 year
Share-based payment award granted maximum vesting period range	5 years
Share-based payment, awards exercise, period minimum	12 months
Share-based payment, awards exercise, period maximum	10 years
Stock Appreciation Right [Member]
Additional Share-based Compensation (Textual) [Abstract]
Granted, Shares	858,000
Restricted Stock Unit [Member]
Additional Share-based Compensation (Textual) [Abstract]
Granted, Shares	145,000

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Share-based payment, awards exercise, period maximum.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, 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

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-Name Accounting Standards Codification

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

-Section F

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- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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-Name Accounting Standards Codification

-Glossary Antidilution

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Diluted Earnings Per Share

-URI http://asc.fasb.org/extlink&oid=6510752

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-Name Accounting Standards Codification

-Topic 260

-SubTopic 10

-Section 50

-Paragraph 1

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-Name Accounting Standards Codification

-Glossary Contingent Stock Agreement

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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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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.

+ References

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- Definition

The maximum vesting term over 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.

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The minimum vesting term over 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.

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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

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- Definition

The weighted average period between the balance sheet date and expiration for all vested portions of options outstanding and currently exercisable (or convertible) under the plan, which may be expressed in a decimal value for number of years.

+ References

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- Definition

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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As of the balance sheet date, the total dollar difference between fair values of the underlying shares reserved for issuance and exercise prices of fully vested and expected to vest options outstanding.

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The weighted-average period between the balance sheet date and expiration date for fully vested and expected to vest options outstanding, which may be expressed in a decimal value for number of years.

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