Cash, Cash Equivalents, Restricted Cash, and Short-term Investments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2013	Dec. 31, 2012
Cash and Cash Equivalents, Restricted Cash and Short-Term Investments [Abstract]
Cash	$ 1,403	$ 930
Money market	2,757	9,084
Total cash and cash equivalents	4,160	10,014	6,139	8,896
Corporate bonds	4,469	6,191
Total short-term investments	4,469	6,191
Total restricted cash	250	375
Total	$ 8,879	$ 16,580