Common stock and convertible preferred stock - Preferred Stock (Details)	1 Months Ended		3 Months Ended		12 Months Ended
	Jun. 30, 2020 USD ($) D $ / shares shares	Jan. 31, 2020 USD ($) shares	Mar. 31, 2021 USD ($) $ / shares shares	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Class of Stock [Line Items]
Gross proceeds				$ 995,000
Series A Preferred Convertible Stock
Class of Stock [Line Items]
Number of shares issued | shares		4,722	388,888		1,226,925	512,826
Issue price per share | $ / shares			$ 9.00		$ 9.00	$ 9.00
Gross proceeds		$ 45,000	$ 3,500,000		$ 11,000,000.0	$ 4,600,000
Payment of IPO costs						$ 35,000
Shares issued for conversion of debt | shares			5,670,184			821,657
Amount of debt converted						$ 6,800,000
Shares purchased by issuing warrants | shares	1,035,196
Exercise price | $ / shares	$ 9.00
Warrants rights term	3 years
Stock price | $ / shares	$ 27.00
Advanced payments for shares				$ 1,000,000.0
Number of trading days | D	10
Number of consecutive trading days | D	20
Fair value	$ 1,500,000