Equity Equity, Textuals (Details) (USD $)	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Preferred Stock, Shares Authorized	1,000,000	1,000,000
Common Stock, Shares Authorized	500,000,000	500,000,000	500,000,000
Common Stock, Shares, Outstanding	211,046,501	211,046,501	222,955,853
Treasury Stock, Shares	10,000	10,000	1,709,542
Treasury Stock, Shares, Acquired		15,294,567	19,752,174	13,927,510
Treasury Stock, Value, Acquired, Par Value Method		$ 184,900,000	$ 195,700,000	$ 116,200,000
Treasury Stock Acquired, Average Cost Per Share		$ 12.09	$ 9.91	$ 8.34
Stock Repurchase Program, Authorization Increase		155,000,000
Stock Repurchase Program, Authorized Amount		200,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount		190,100,000
Dividends declared per share	$ 0.06	$ 0	$ 0	$ 0
Payments of Dividends, Common Stock		$ 60,296,000	$ 44,795,000	$ 40,001,000