Common stock Common stock issuance (Details 2) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Common Stock, Shares Authorized	500,000,000	500,000,000
Common Stock, Shares, Issued	204,162,814	203,889,661
Proceeds from Issuance of Common Stock	$ (149,000)	$ 88,767,000	$ 3,385,000
At-the-market offering
Class of Stock [Line Items]
Common Stock, Shares Authorized	6,400,000
Common Stock, Shares, Issued	0	2,800,000
Common Stock, Authorized Shares Remaining	3,600,000
Proceeds from Issuance of Common Stock	$ (100,000)	$ 88,800,000
Payments of Stock Issuance Costs	$ 149,000	$ 1,200,000
K-Plan
Class of Stock [Line Items]
Common Stock, Authorized Shares Remaining	7,200,000