Organization and Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 item	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Organization and Summary of Significant Accounting Policies
Cash and cash equivalents	$ 9,226	$ 13,638	$ 36,733	$ 5,530
Number of reportable segments	1
Period for which no sufficient cash was available to sustain operations	1 year
Minimum period of uncertainty regarding the entity's ability to maintain liquidity sufficient to operate business effectively	12 months