Stockholders' Equity - June 2020 Equity Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Jun. 30, 2021	Jan. 31, 2020	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amount paid for clearing fees	$ 19
Warrants issued (in shares)			229,414	310,860
Proceeds from the exercise of warrants			$ 0
January 2020 Institutional Investor
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Securities called by warrants (in shares)		688,360
Sale of common stock (USD per share)		$ 3.3700
Purchase price (USD per share)		0.625
Investor Warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Sale of common stock (USD per share)	$ 5.05
Exercise price of common stock (USD per share)		$ 3.37
Amount paid for placement agent commissions	$ 400
Amount paid related to expenses for registered direct offering and concurrent private placement	51
Offering costs paid on the issuance of common stock and warrants					$ 470
Proceeds from sale of common stock and warrants	$ 4,500
Warrants issued (in shares)			187,734	269,180
January 2020 Equity Offering
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price of common stock (USD per share)			$ 3.67	$ 3.59
Amount paid for placement agent commissions		$ 193
Amount paid related to expenses for registered direct offering and concurrent private placement		50
Amount paid for clearing fees		231
Offering costs paid on the issuance of common stock and warrants					$ 510
Proceeds from sale of common stock and warrants		$ 2,300
Warrants issued (in shares)			229,414	310,860
Estimated proceeds from issuance of warrants			$ 800
Issuance of common stock upon the exercise of warrants (in shares)			0	156,446
Proceeds from the exercise of warrants				$ 527
January 2020 Equity Offering, Private Placement
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Securities called by warrants (in shares)		48,185
Exercise price of common stock (USD per share)		$ 4.9940
Warrants issued (in shares)			41,680	41,680