Common stock Common stock issuance (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Shares, Issued	203,889,661	201,061,198
Proceeds from Issuance of Common Stock	$ 88,767	$ 3,385	$ 106,848
At-the-market offering
Class of Stock [Line Items]
Common Stock, Shares Authorized	6,400,000
Common Stock, Shares, Issued	2,800,000	0
Proceeds from Issuance of Common Stock	$ 88,800	$ 0
Payments of Stock Issuance Costs	$ 1,200	$ 0
Common Stock, Authorized Shares Remaining	3,600,000
K-Plan
Class of Stock [Line Items]
Common Stock, Authorized Shares Remaining	7,200,000