Warrants (Narrative) (Details)	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Class of Warrant or Right [Line Items]
Common stock exercise price	8.68	8.03	6.87
Maximum [Member]
Class of Warrant or Right [Line Items]
Common stock exercise price	10.13
Minimum [Member]
Class of Warrant or Right [Line Items]
Common stock exercise price	7.73