Common Stock (Details) (USD $) In Thousands, except Share data in Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Sep. 30, 2009	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Common Stock (Textual) [Abstract]
Common shares issued in offering	46
Common stock issued, net of expenses	$ 318,400	$ 18	$ (95)	$ 318,406