Underwritten public offerings (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions				12 Months Ended
	Feb. 03, 2021	Aug. 06, 2020	Aug. 08, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Subsidiary or Equity Method Investee [Line Items]
Sale of common stock in underwritten public offering, net (in shares)			2.7
Common stock, par value				$ 0.001	$ 0.001
Underwritten public offering
Subsidiary or Equity Method Investee [Line Items]
Sale of common stock in underwritten public offering, net (in shares)	4.1	3.0	2.7
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Gross proceeds	$ 287,500	$ 97,600	$ 69,000
Stock issuance cost	17,800	6,200	4,500
Proceeds from sale of common stock, net of issuance costs	$ 269,700	$ 91,400	$ 64,500	$ 269,718	$ 91,404	$ 64,529