Subsequent Event (Details) (USD $) In Millions, except Share data, unless otherwise specified	2 Months Ended
Feb. 16, 2012	May 01, 2012
Subsequent Event [Line Items]
Shares of Common Stock Repurchased Between Period End Date and Filing Date	282,090
Shares of Common Stock Repurchase Executed Before the Balance Sheet Date but Settled After the Balance Sheet Date	60,200
Average Price Per Share of Common Stock Repurchased Between Period End Date and Filing Date	$ 37.56
Business Acquisition, Cost of Acquired Entity, Purchase Price		$ 100

Average Price Per Share of Common Stock Repurchased Between Period End Date and Filing Date

No definition available.

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- Definition

Shares of Common Stock Repurchased Between Period End Date and Filing Date

+ References

No definition available.

+ Details

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- Definition

Shares of Common Stock Repurchase Executed Before the Balance Sheet Date but Settled After the Balance Sheet Date

+ References

No definition available.

+ Details

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- Definition

The total cost of the acquired entity including the cash paid to shareholders of acquired entities, fair value of debt and equity securities issued to shareholders of acquired entities, the fair value of the liabilities assumed, and direct costs of the acquisition.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141

-Paragraph 51

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

+ Details

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Balance Type:	debit
Period Type:	instant

- Details

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