Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 38,811	$ 43,159
Marketable securities, available-for-sale	17,036	37,639
Restricted cash	3,119	3,059
Receivables and other assets	1,829	2,152
Total current assets	60,795	86,009
Long-term investments	2,039	2,225
Property and equipment, net	4,353	5,284
Intangible assets, net	2,115	2,813
Other assets	192	191
Total assets	69,494	96,522
Current liabilities:
Accounts payable and accrued expenses	5,173	5,629
Deferred revenue	37	150
Total current liabilities	5,210	5,779
Long-term liabilities:
Deferred rent	1,391	1,657
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.01 par value, 5,000 shares authorized, none issued and outstanding
Common stock, $0.01 par value, 160,000 shares authorized, 86,760 and 86,136 shares issued and outstanding at September 30, 2013, and December 31, 2012, respectively	868	861
Additional paid-in capital	438,939	435,915
Accumulated deficit	(376,983)	(347,937)
Accumulated other comprehensive income	69	247
Total stockholders' equity	62,893	89,086
Total liabilities and stockholders' equity	$ 69,494	$ 96,522