Stock-Based Compensation (Details) (Textual) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Stock-Based Compensation (Textual) [Abstract]
Estimate forfeiture rate share based compensation arrangement	0.06	0.05	0.05
Weighted-average fair value of option granted	$ 4.20	$ 3.09	$ 2.88
Fair value of options vested	$ 7.1
Total realized tax benefit	2.0	0.3
Issuance of Restricted Stocks Fair Value	10.5
Total unamortized stock-based compensation cost related to unvested stock options and restricted stock units	$ 30.9
Remaining weighted-average amortization period	2.5
Employee Stock Purchase Plan [Member]
Stock-Based Compensation (Textual) [Abstract]
Weighted-average fair value other than option granted	$ 2.15	$ 1.70	$ 2.19
Discount percentage on purchase of stock	15.00%
Value of stock purchase right percentage of call option	85.00%
Value of stock purchase right percentage of put option	15.00%

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Discount percentage on purchase of stock.

+ References

No definition available.

+ Details

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- Definition

Estimate forfeiture rate share based compensation arrangement.

+ References

No definition available.

+ Details

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- Definition

Fair Value of options vested.

+ References

No definition available.

+ Details

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- Definition

Issuance of restricted stocks fair value.

+ References

No definition available.

+ Details

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- Details

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- Definition

Value of stock purchase right percentage of call option.

+ References

No definition available.

+ Details

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- Definition

value of stock purchase right percentage of put option.

+ References

No definition available.

+ Details

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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

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.

+ References

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- Definition

Disclosure of the aggregate tax benefit realized from the exercise of stock options and the conversion of similar instruments during the annual period.

+ References

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- 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 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.

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 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

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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

+ References

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