Common Stock - Summary of Common Stock Issued and Reserved for Issuance (Details) - shares	Mar. 31, 2020	Dec. 31, 2019
Stockholders Deficit [Line Items]
Shares of common stock issued	18,726,000	18,645,000
Shares of common stock reserved for issuance for:
Total shares of common stock issued and reserved for issuance	23,979,000	23,046,000
Common Stock Warrants Outstanding
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	105,000	105,000
Stock Options Outstanding
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	2,324,000	2,415,000
Restricted Stock Units Outstanding
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	1,522,000	245,000
Shares Available for Grant Under Stock Incentive Plan
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	694,000	1,215,000
Shares Available for Sales Under Employee Stock Purchase Plan
Shares of common stock reserved for issuance for:
Shares of common stock reserved for issuance	608,000	421,000