Cash and Investments (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Dec. 31, 2010
Cash, cash equivalents, short-term investments, and restricted cash
Cash	$ 2,022	$ 1,428
Cash equivalents:
Total cash equivalents	4,875	7,077
Total cash and cash equivalents	6,897	8,505	9,053	10,814
Short-term investments:
Total short-term investments	11,782	9,619
Total cash, cash equivalents, investments and restricted cash	19,554	18,999
Corporate debt [Member]
Cash equivalents:
Total cash equivalents	450	501
Money market funds [Member]
Cash equivalents:
Total cash equivalents	4,425	6,576
Short-term investments:
Restricted cash-money market fund	875	875
U.S. agency securities [Member]
Short-term investments:
Total short-term investments		1,751
Municipal securities [Member]
Short-term investments:
Total short-term investments	355	355
Corporate commercial paper [Member]
Short-term investments:
Total short-term investments	5,373	1,250
Foreign government bonds [Member]
Short-term investments:
Total short-term investments		500
Corporate debt [Member]
Short-term investments:
Total short-term investments	$ 6,054	$ 5,763