Common stock (Details) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended			3 Months Ended	9 Months Ended
	Mar. 03, 2020	Feb. 27, 2020	Aug. 31, 2021	Aug. 31, 2017	Mar. 31, 2017	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Subsidiary, Sale of Stock [Line Items]
Proceeds from the issuance of common stock, net								$ 106,059
Common stock
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)						46,511,628
Private Investment in Public Equity (PIPE)
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)		46,511,628
Share price (in dollars per share)		$ 2.15
Share price premium (as percentage)		12.60%
Share price, prior to premium price (in dollars per share)		$ 1.91
Proceeds from the issuance of common stock, net	$ 93,800
At-the-market equity offering program | Common stock
Subsidiary, Sale of Stock [Line Items]
Shares issued (in shares)							0	6,769,559
Proceeds from the issuance of common stock, net								$ 12,200
Maximum value of common stock allowed to be sold				$ 75,000	$ 35,000
Shares, Outstanding							18,287,913
Net proceeds from issuance of stock							$ 59,600
At-the-market equity offering program | 2021 ATM Program | Common stock
Subsidiary, Sale of Stock [Line Items]
Maximum value of common stock allowed to be sold			$ 100,000