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Consolidated Statements Of Stockholders' Equity (Parenthetical)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Consolidated Statements Of Stockholders' Equity [Abstract]
Repurchase of Class A Common Stock, shares	4,353,801	3,349,286	3,173,182
Issuance of treasury shares upon exercise of stock options, purchases under stock purchase plan and grants of restricted stock awards, shares	809,084	765,078	691,176

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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