Stockholders' equity (Details)								9 Months Ended
	Jul. 28, 2021 USD ($) $ / shares shares	Jul. 26, 2021 USD ($) shares	Jul. 06, 2021 USD ($) $ / shares shares	Mar. 29, 2021 shares	Mar. 02, 2021 shares	Jan. 20, 2021 shares	Dec. 31, 2020 $ / shares shares	Sep. 30, 2021 USD ($) $ / shares shares	Sep. 30, 2020 USD ($)	Aug. 30, 2021 $ / shares shares	Mar. 05, 2021 shares	Mar. 05, 2020 $ / shares	Dec. 31, 2019 $ / shares shares
Stockholders' equity (Details) [Line Items]
Common stock, shares authorized (in shares)							110,000,000	110,000,000
Common stock, shares issued (in shares)							50,878,780	65,121,241
Common stock, shares outstanding (in shares)							50,878,780	65,121,241
Sale of stock, price per share (in dollars per share) | $ / shares			$ 15.03
Common stock, par value (in dollars per share) | $ / shares							$ 0.0001	$ 0.0001				$ 0.0001
Proceeds from exercise of public warrants | $								$ 48,145,000	$ 0
Exercise price (in dollars per share) | $ / shares								$ 11.50
GDI
Stockholders' equity (Details) [Line Items]
Preferred stock shares, outstanding (in shares)													1,000,000
Preferred shares, par value (in dollars per share) | $ / shares													$ 0
Preferred stock, conversion ratio													1
Common stock, par value (in dollars per share) | $ / shares												$ 0.0001
Follow On Public Offering
Stockholders' equity (Details) [Line Items]
Sale of stock, number of shares issued in transaction (in shares)			11,600,000
Follow On Public Offering - Shares From Parent
Stockholders' equity (Details) [Line Items]
Sale of stock, number of shares issued in transaction (in shares)			5,500,000
Sale of stock, consideration received on transaction | $			$ 78,300,000
Follow On Public Offering - Shares From Selling Shareholders
Stockholders' equity (Details) [Line Items]
Sale of stock, number of shares issued in transaction (in shares)			6,100,000
Sale of stock, consideration received on transaction | $			$ 0
Earnout Shares
Stockholders' equity (Details) [Line Items]
Shares issued subject to earnout provisions (in shares)											1,200,000
Contingent earnout shares expected to vest, threshold trading term								20 days
Contingent earnout shares expected to vest, trading period								30 days
Earnout shares vested (in shares)				400,001	400,000	399,999	0
Earnout Shares One
Stockholders' equity (Details) [Line Items]
Contingent earnout shares expected to vest (in shares)								399,999
Contingent earnout shares expected to vest, exercise price (in dollars per share) | $ / shares								$ 12.00
Earnout Shares Two
Stockholders' equity (Details) [Line Items]
Contingent earnout shares expected to vest (in shares)								400,000
Contingent earnout shares expected to vest, exercise price (in dollars per share) | $ / shares								$ 13.50
Earnout Shares Three
Stockholders' equity (Details) [Line Items]
Contingent earnout shares expected to vest (in shares)								400,001
Contingent earnout shares expected to vest, exercise price (in dollars per share) | $ / shares								$ 15.00
Public Warrant
Stockholders' equity (Details) [Line Items]
Warrants exercised (in shares)	2,750,000	1,400,000
Proceeds from exercise of public warrants | $	$ 31,700,000	$ 16,400,000
Warrants outstanding (in shares)	2,800,000							0
Redemption price (in dollars per share) | $ / shares										$ 0.01
Exercise price (in dollars per share) | $ / shares	$ 11.50
Warrants redeemed (in shares)										19,744
Private Warrant
Stockholders' equity (Details) [Line Items]
Warrants outstanding (in shares)								0
Common Stock
Stockholders' equity (Details) [Line Items]
Common stock, shares authorized (in shares)								110,000,000
Common stock, shares issued (in shares)											50,800,000
Common stock, shares outstanding (in shares)								65,100,000