Leases - Lease liabilities maturities (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
Maturities of lease liabilities
2020	$ 66
2021	52
2022	43
2023	32
2024	21
Thereafter	88
Future value of lease liabilities	302
Less: Imputed interest	(63)
Present value of lease liabilities	$ 239
Leases not yet commence, term	10 years
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent us-gaap:OtherLiabilitiesNoncurrent