CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY (Parenthetical)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Repurchase of Class A Common Stock, shares	1,356,861	1,473,863	4,353,801
Issuance of treasury shares upon exercise of stock options, purchases under stock purchase plan and grants of restricted stock awards, shares	980,999	488,863	809,084
Additional Paid-in Capital [Member]
Issuance of treasury shares upon exercise of stock options, purchases under stock purchase plan and grants of restricted stock awards, shares	980,999	488,863	809,084
Treasury Stock [Member]
Repurchase of Class A Common Stock, shares	1,356,861	1,473,863	4,353,801
Issuance of treasury shares upon exercise of stock options, purchases under stock purchase plan and grants of restricted stock awards, shares	980,999	488,863	809,084