Common stock and convertible preferred stock - Preferred Stock (Details)	1 Months Ended	6 Months Ended		12 Months Ended
	Jan. 31, 2020 USD ($) shares	Jun. 30, 2021 USD ($) $ / shares shares	Jun. 30, 2020 USD ($) D $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares
Class of Stock [Line Items]
Gross proceeds			$ 11,046,000
Payment of IPO costs			$ 27,000
Series A Preferred Convertible Stock
Class of Stock [Line Items]
Number of shares issued | shares	4,722	388,888	1,226,925	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
Net proceeds from Series A Preferred shares			$ 9,500,000
Exercise price | $ / shares			$ 9.00
Warrants rights term			3 years
Stock price | $ / shares			$ 27.00
Number of trading days | D			10
Number of consecutive trading days | D			20
Fair value			$ 1,500,000