Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Current assets
Cash and cash equivalents	$ 13,115	$ 40,155
Short-term investments	112,357	49,335
Accounts receivable from related party	291	507
Prepaid expenses and other current assets	750	1,322
Total current assets	126,513	91,319
Property and equipment, net	1,198	1,541
Long-term investments	2,773	6,596
Other assets	160	2,095
Total assets	130,644	101,551
Current liabilities:
Accounts payable	574	536
Accrued liabilities	6,023	4,692
Deferred revenue from related party	4,513	3,628
Current portion of equipment financing obligations	517	501
Total current liabilities	11,627	9,357
Noncurrent equipment financing obligations	523	947
Deferred revenue from related party	376	4,535
Convertible note from related party		10,472
Other non-current liabilities	113	243
Total liabilities	12,639	25,554
Commitments
Preferred stock:
Common stock, $0.001 par value, 200,000,000 shares and 68,000,000 shares authorized at September 30, 2012 and December 31, 2011, respectively; 36,204,792 shares and 4,385,439 shares issued and outstanding at September 30, 2012 and December 31, 2011, respectively, net of shares subject to repurchase	36	4
Additional paid-in capital	242,326	170,289
Employee note receivable	(16)	(16)
Accumulated other comprehensive income (loss)	51	(31)
Accumulated deficit	(124,392)	(94,298)
Total stockholders' equity	118,005	75,997
Total liabilities and stockholders' equity	130,644	101,551
Convertible preferred stock
Preferred stock:
Convertible preferred stock $0.001 par value; no shares and 48,989,914 shares authorized and issuable in Series A to E at September 30, 2012 and December 31, 2011, respectively; no shares and 48,664,392 shares issued and outstanding at September 30, 2012 and December 31, 2011, respectively; aggregate liquidation preference of $0 and $165,096 at September 30, 2012 and December 31, 2011, respectively;		49
Other preferred stock
Preferred stock:
Preferred stock, $0.001 par value, 10,000,000 shares authorized; no shares issued and outstanding;