Stockholders' equity (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	Mar. 22, 2021	Mar. 31, 2021	Dec. 31, 2020
Stockholders' equity
Common stock, shares issued	10,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001	$ 0.0001
Public offering price	$ 40
Proceeds from common stock		$ 380
Net transaction fee		$ 20
Series A Junior Participating Preferred Stock
Stockholders' equity
Preferred stock, authorized shares		2.4	2.4
Preferred stock, shares outstanding		0	0
Common Stock
Stockholders' equity
Common stock, shares issued		10,000,000.0