Equity Incentive Plans - Employee Stock Purchase Plan (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant, Beginning balance	608,528
Shares Available for Grant, Shares authorized	2,490,417
Shares Available for Grant, Ending balance	1,196,746
Options Issued and Outstanding Number of Shares, Beginning balance	5,506,760
Options Issued and Outstanding Number of Shares, Ending balance	7,272,768
2014 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares Available for Grant, Beginning balance	680,322
Shares Available of Grant, Shares purchased	(160,744)
Shares Available for Grant, Ending balance	519,578
Options Issued and Outstanding Number of Shares, Beginning balance	330,936
Number of shares issued under ESPP	160,744
Options Issued and Outstanding Number of Shares, Ending balance	491,680
Purchase Price per Share | $ / shares	$ 2.48
Gross Proceeds | $	$ 396