CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Revenue:
License and other revenue	$ 2,073	$ 237
Type of Revenue [Extensible List]	snss:LicenseAndOtherRevenueMember	snss:LicenseAndOtherRevenueMember
Operating expenses:
Research and development	$ 15,412	$ 14,615
General and administrative	9,949	11,332
Total operating expenses	25,361	25,947
Loss from operations	(23,288)	(25,710)
Interest expense	(514)	(1,154)
Other income, net	472	249
Net loss	(23,330)	(26,615)
Unrealized gain on available-for-sale securities	1	7
Comprehensive loss	(23,329)	(26,608)
Basic and diluted loss per common share:
Net loss:	$ (23,330)	$ (26,615)
Shares used in computing net basic and diluted loss per common share:	87,129	35,582
Net loss per common share:	$ (0.27)	$ (0.75)