Cash and Available for Sale Securities (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash and cash equivalents [Abstract]
Cash	$ 1,203,000	$ 7,205,000
Cash equivalents [Abstract]
Total cash equivalents	5,149,000	10,745,000
Total cash and cash equivalents	6,352,000	17,950,000	22,119,000
Short-term investments [Abstract]
Total short-term investments	9,506,000	6,809,000
Total cash, cash equivalents and short-term investments	15,858,000	24,759,000
Contractual maturities of cash and short term investments	1 year
Long-term investments	0	0
Money Market Mutual Funds [Member]
Cash equivalents [Abstract]
Total cash equivalents	249,000	1,045,000
Certificates of Deposit [Member]
Cash equivalents [Abstract]
Total cash equivalents	500,000	3,100,000
Short-term investments [Abstract]
Total short-term investments	3,301,000	3,278,000
Commercial Paper [Member]
Cash equivalents [Abstract]
Total cash equivalents	4,400,000	6,600,000
Short-term investments [Abstract]
Total short-term investments	4,947,000	1,500,000
Corporate Bonds [Member]
Short-term investments [Abstract]
Total short-term investments	$ 1,258,000	$ 2,031,000