Preferred Stock (Details 2) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 2008 Warrants	Aug. 29, 2011 2008 Warrants	Jul. 28, 2008 2008 Warrants	Dec. 31, 2012 2010 Warrants	Aug. 29, 2011 2010 Warrants	Dec. 14, 2010 2010 Warrants
Preferred Stock
Common stock that can be purchased on exercise of warrants issued in consideration for obligations under debt instrument (in shares)				240,000	240,000		3,495,000	3,495,000
Exercise price of warrants (in dollars per share)			9.05	9.05		3.84
Warrants outstanding	3,735,000	3,735,000
Cash distribution in exchange for Preferred Equity Interests	$ 6