Organization and Summary of Significant Accounting Policies - Adoption of ASC 842 - Tabular Disclosure (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Jan. 31, 2019	Jan. 01, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset	$ 4,300	$ 4,877	$ 4,877
Total assets	167,202	142,065		$ 137,188
Operating lease liabilities, current	1,230	1,116	1,116
Operating lease liabilities, non-current	4,726	5,917	$ 5,917
Deferred rent				2,404
Total liabilities	108,426	79,075		74,446
Accumulated deficit	(147,892)	(121,036)		(121,284)
Total stockholders' equity	58,776	62,990		62,742	$ 32,950	$ 16,365
Total liabilities and stockholders' equity	$ 167,202	142,065		$ 137,188
Accounting Standards Update 2016-02 [Member] | Restatement Adjustment [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use asset		4,877
Total assets		4,877
Operating lease liabilities, current		1,116
Operating lease liabilities, non-current		5,917
Deferred rent		(2,404)
Total liabilities		4,629
Accumulated deficit		248
Total stockholders' equity		248
Total liabilities and stockholders' equity		$ 4,877