Employee benefit plans - Components of net periodic benefit cost (Details) - Pension - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Employee benefit plans
Interest cost	$ 4	$ 3	$ 11	$ 10
Expected return on plan assets	(7)	(7)	(22)	(21)
Amortization of net loss		1		4
Expenses paid	1	1	2	2
Net periodic benefit credit	$ (2)	$ (2)	$ (9)	$ (5)