Debts - Additional Information (Details)		1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 12, 2020 USD ($) shares $ / shares	Dec. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jul. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Apr. 04, 2018 USD ($)	Oct. 31, 2017 USD ($)
Line of Credit Facility [Line Items]
Aggregate principal amount of loans outstanding			$ 35,898,000
Accrued interest on promissory note			37,000	$ 37,000	$ 150,000	$ 150,000
Outstanding balance on line of credit facility		$ 10,200,000	10,200,000		10,200,000	10,500,000
Changes in fair value of promissory note			699,000	(2,321,000)	(927,000)	167,000
Maximum number of shares of common stock issuable (in shares) | shares	3,076,171
Conversion price per share on convertible note payable (in dollars per share) | $ / shares	$ 5.12
Interest expense			187,000	189,000	760,000	758,000
Term of cooperation and development agreement.		3 years
Deferred revenue		$ 674,000	505,000		674,000	0
Accounts Payable and Accrued Liabilities
Line of Credit Facility [Line Items]
Interest expense			153,000	0	915,000	496,000
Yaskawa
Line of Credit Facility [Line Items]
Letter of intent for development activities	$ 4,000,000.0	4,000,000.0
Proceeds from collaborators		1,000,000.0
Deferred revenue		667,000	334,000		667,000
Loan and Security Agreement (LSA)
Line of Credit Facility [Line Items]
Long-term loan facility									$ 15,000,000.0
Aggregate principal amount of loans outstanding		10,000,000.0	10,000,000.0		10,000,000.0	15,000,000.0
Tranche A Loan
Line of Credit Facility [Line Items]
Long-term loan facility									5,000,000.0
Tranche B Loan
Line of Credit Facility [Line Items]
Long-term loan facility							$ 8,000,000.0	$ 8,000,000	10,000,000
Tranche B-1 Loan
Line of Credit Facility [Line Items]
Long-term loan facility						2,000,000		$ 2,000,000
Tranche C Note
Line of Credit Facility [Line Items]
Long-term loan facility									10,000,000.0
Revolving loan									$ 10,000,000.0
Interest rate per annum									6.00%
Accrued interest on promissory note			$ 150,000	152,000	610,000	608,000
Yaskawa Note
Line of Credit Facility [Line Items]
Interest rate per annum			1.00%							1.00%
Changes in fair value of promissory note			$ (699,000)		927,000	(167,000)
Unsecured subordinated convertible promissory note		15,486,000	15,523,000		15,486,000	15,336,000				$ 15,000,000.0
Maximum number of shares of common stock issuable (in shares) | shares	3,076,171
Interest expense			37,000	$ 37,000	150,000	150,000
Accrued interest on promissory note		$ 486,000	$ 523,000		$ 486,000	$ 336,000