Stockholders' Equity (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2007	Dec. 31, 2006	Dec. 31, 2005	Dec. 31, 2004
Options granted during period (in shares)	2,136,000	1,190,500	861,000
Weighted average exercise price	$ 3.26	$ 6.91	$ 3.10	$ 1.99	$ 6.11	$ 5.72	$ 3.61	$ 2.66	$ 0.56
Weighted average grant date fair value	$ 2.21	$ 4.60	$ 2.24