Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Schedule of fair value of financial assets and liabilities measured at fair value and classification by level of input

The following tables summarize the fair value of financial assets (marketable securities) that are measured at fair value, and the classification by level of input within the fair value hierarchy: 

	Fair Value Measurements as of
	December 31, 2019
	Level 1		Level 2		Level 3		Total
Investments:
Money market funds	$	71	$	—	$	—	$	71
Total assets measured at fair value	$	71	$	—		—	$	71

	Fair Value Measurements as of
	December 31, 2018
	Level 1		Level 2		Level 3		Total
Investments:
Money market funds	$	71	$	—	$	—	$	71
Total assets measured at fair value	$	71	$	—		—	$	71

Schedule of antidilutive securities excluded from computations of diluted net loss per common share

The following shares subject to outstanding potentially dilutive securities have been excluded from the computations of diluted net loss per common share as the effect of including such securities would be antidilutive:

	Year Ended December 31,
	2019		2018
Options to purchase common stock		15,881,721		15,409,357
Warrants to purchase common stock		331,193		331,193
		16,212,914		15,740,550

Schedule of composition of cash, cash equivalents and restricted cash

As a result of the adoption, the Company will no longer present the change within restricted cash in the consolidated statements of cash flows. See below for the composition of cash, cash equivalents and restricted cash shown on the statements of cash flow:

	Year Ended December 31,
	2019		2018
Cash and cash equivalents	$	143	$	814
Restricted cash		71		71
Total cash, cash equivalents and restricted cash as shown on statement of cash flows	$	214	$	885