Basis of Presentation and Summary of Significant Accounting Policies - Net Loss per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Options
Impairment Effects on Earnings Per Share [Line Items]
Securities excluded from net loss per share calculation (less than for options in the three months ended June 30, 2020) (in shares)	41	117	60	57
Warrants
Impairment Effects on Earnings Per Share [Line Items]
Securities excluded from net loss per share calculation (less than for options in the three months ended June 30, 2020) (in shares)	11	321	56	152
Restricted share units
Impairment Effects on Earnings Per Share [Line Items]
Securities excluded from net loss per share calculation (less than for options in the three months ended June 30, 2020) (in shares)		13		7
Convertible securities
Impairment Effects on Earnings Per Share [Line Items]
Securities excluded from net loss per share calculation (less than for options in the three months ended June 30, 2020) (in shares)	175	519	289	531