CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue:
License and other revenue		$ 237
Type of Revenue [Extensible List]	snss:LicenseAndOtherRevenueMember	snss:LicenseAndOtherRevenueMember
Operating expenses:
Research and development	$ 3,248	$ 3,969
General and administrative	2,439	3,359
Total operating expenses	5,687	7,328
Loss from operations	(5,687)	(7,091)
Interest expense	(261)	(281)
Other income, net	88	99
Net loss	(5,860)	(7,273)
Unrealized gain on available-for-sale securities		2
Comprehensive loss	(5,860)	(7,271)
Basic and diluted loss per common share:
Net loss	$ (5,860)	$ (7,273)
Shares used in computing net loss per common share	59,142	34,345
Net loss per common share	$ (0.10)	$ (0.21)