Equity (Details Textual) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended				1 Months Ended	12 Months Ended		1 Months Ended
	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Feb. 28, 2011	Jan. 31, 2012 Common stock	Dec. 31, 2011 Common stock	Dec. 31, 2010 Common stock	Mar. 31, 2011 Series A [Member]	Dec. 31, 2011 Series A [Member]	Dec. 31, 2010 Series A [Member]	Dec. 31, 2011 Series X Junior Participating [Member]	Dec. 31, 2010 Series X Junior Participating [Member]
Class of Stock [Line Items]
Preferred stock, shares authorized		8,000,000	8,000,000							1,750,000	1,750,000	1,000,000	1,000,000
Preferred stock, shares issued		0	8,000							0	8,221	0	0
Preferred stock, shares outstanding		0	8,000							0	8,221	0	0
Series A Preferred Stock shares Redeemed									8,221
Repurchase of common stock, shares						3,500,000	6,000,000	40,300,000
Repurchase of common stock, value		$ 497,975	$ 2,077,579	$ 751,170		$ 401,500	$ 498,000	$ 2,100,000
Common stock available for repurchase						10,500,000
Equity (Textual) [Abstract]
Total number of common stock shares issued on conversion of Series A Preferred Stock	493,260
Common stock shares authorized for repurchase					20,000,000