Contract revenue - Narrative (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021
Capitalized Contract Cost [Line Items]
Contract with customer, asset	$ 2,500			$ 2,500		$ 2,500
Contract assets representing accrued revenues not yet billed	79			79		42
Contract with customer, liability	193			193		163
Contract with customer, liability, revenue recognized	63			85
Incremental costs for obtaining contracts
Capitalized Contract Cost [Line Items]
Capitalized contract costs	$ 60			$ 60		64
Capitalized contract cost, amortization period	9 years			9 years
Capitalized contract cost, amortization	$ 4	$ 5	$ 5	$ 9	$ 10
Costs to fulfill contract
Capitalized Contract Cost [Line Items]
Capitalized contract costs	20			20		$ 23
Capitalized contract cost, amortization	$ 1	$ 1	$ 1	$ 1	$ 1
Costs to fulfill contract | Minimum
Capitalized Contract Cost [Line Items]
Capitalized contract cost, amortization period	7 years			7 years
Costs to fulfill contract | Maximum
Capitalized Contract Cost [Line Items]
Capitalized contract cost, amortization period	9 years			9 years