Consolidated Balance Sheets (unaudited) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2014 Series A-1 Preferred Stock [Member]	Dec. 31, 2013 Series A-1 Preferred Stock [Member]	Sep. 30, 2014 Series B Preferred Stock [Member]	Dec. 31, 2013 Series B Preferred Stock [Member]	Sep. 30, 2014 Series C Preferred Stock [Member]	Dec. 31, 2013 Series C Preferred Stock [Member]	Sep. 30, 2014 Series D Preferred Stock [Member]
Current assets:
Cash and cash equivalents	$ 3,239	$ 2,793
Available-for-sale investments	18,447	2,359
Prepaid expenses	168	61
Other current assets	27	78
Short-term deposits	39	39
Total current assets	21,920	5,330
Property and equipment, net	86	62
Deferred tax asset		267
Other non-current assets	2,173
Total assets	24,179	5,659
Current liabilities:
Convertible notes, including accrued interest of $0 and $112 as of September 30, 2014 and December 31, 2013, respectively		3,727
Derivative liability		1,443
Accounts payable	1,048	399
Accrued expenses	1,610	984
Deferred tax liability		267
Current portion of deferred revenue from sale of option to acquire company		2,948
Total current liabilities	2,658	9,768
Non-current liabilities:
Investors' rights/obligations	11,903
Total liabilities	14,561	9,768
Commitments and contingencies
Redeemable convertible preferred stock,	35,416	34,230	18,003	17,374	29,083	27,401	18,265	17,400	25,402
Accumulated deficit	(116,540)	(100,514)
Accumulated other comprehensive loss	(11)
Total stockholders’ deficit	(116,551)	(100,514)
Total liabilities, redeemable convertible preferred stock and stockholders’ deficit	$ 24,179	$ 5,659