Employee benefit plans - Components of net periodic benefit cost (Details) - Pension - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Employee benefit plans
Interest cost	$ 3	$ 4	$ 7	$ 7
Expected return on plan assets	(8)	(7)	(15)	(14)
Amortization of net loss		2		3
Expenses paid			1	1
Net periodic benefit credit	$ (5)	$ (1)	$ (7)	$ (3)