Summary of Significant Accounting Policies - Reconciliation of Basic and Diluted Income (Loss) per Share (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net loss	$ (1,308)	$ (946)	$ (2,254)	$ (2,865)	$ (3,000)	$ (1,920)	$ (1,801)	$ (2,390)	$ (7,373)	$ (9,111)	$ (11,267)
Denominator:
Basic and diluted weighted average common shares outstanding									12,309	11,997	11,806