Stockholders' Equity (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	9 Months Ended	12 Months Ended
Nov. 08, 2012	Sep. 30, 2012	Dec. 31, 2011
Stockholders' Equity Note [Abstract]
Stock Repurchased During Period, Shares	1,670	6,422
Stock Repurchased During Period, Value	$ 13,266	$ 47,401
Change in the number of shares of Class A common stock outstanding
Shares outstanding as of beginning of period	86,707	92,433	91,725
Shares issued as part of equity-based compensation plans and the Employee Stock Purchase Plan ("ESPP"), net of RSUs surrendered		696	708
Shares repurchased into treasury stock		(6,422)	0
Shares outstanding as of end of period		86,707	92,433

Total number of shares of common stock held by shareholders. May be all or portion of the number of common shares authorized. These shares represent the ownership interest of the common shareholders. Shares outstanding equals shares issued minus shares held in treasury and other adjustments, if any.

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Number of shares (or other type of equity) issued during the period as a result of any equity-based compensation plan other than an employee stock ownership plan (ESOP), net of any shares forfeited. Shares issued could result from the issuance of restricted stock, the exercise of stock options, stock issued under employee stock purchase plans, and/or other employee benefit plans.

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- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

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