Stockholders' Equity (Deficit) - At The Market Issuances (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stockholders' Equity (Deficit)
Value of shares sold by the entity			$ 173,805
At-The-Market Issuance Sales Agreement
Stockholders' Equity (Deficit)
Number of shares sold by the entity	0	0	215,539
Value of shares sold by the entity			$ 3,500
Net proceeds after deducting commissions and other transactions costs			$ 3,400