Warrants Schedule of Gain (Loss) on Warrants (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Common Stock Warrants [Line Items]
Change in fair value of warrant liability	$ (2,284,000)	$ 509,000	$ 2,496,000
2017 Placement Warrants Liability
Schedule Of Common Stock Warrants [Line Items]
Change in fair value of warrant liability	(1,705,000)	367,000	2,554,000
2016 Placement Warrants Liability
Schedule Of Common Stock Warrants [Line Items]
Change in fair value of warrant liability	$ (579,000)	$ 142,000	$ (59,000)