Leases - Supplemental balance sheet information (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Operating leases:
Operating lease right-of-use assets (included in Other assets)	$ 138	$ 203
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other Assets, Noncurrent	Other Assets, Noncurrent
Current operating lease liabilities (included in Other current liabilities)	$ 45	$ 65
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other Liabilities, Current	Other Liabilities, Current
Noncurrent operating lease liabilities (included in Other long-term liabilities)	$ 93	$ 138
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent
Total operating lease liabilities	$ 138	$ 203
Operating Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesCurrent us-gaap:OtherLiabilitiesNoncurrent	us-gaap:OtherLiabilitiesCurrent us-gaap:OtherLiabilitiesNoncurrent
Finance leases:
Property, plant and equipment	$ 154	$ 107
Accumulated amortization	(42)	(33)
Net property, plant and equipment	112	74
Current finance lease liabilities (included in Long-term debt due within one year)	$ 16	$ 7
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Long-term Debt, Current Maturities	Long-term Debt, Current Maturities
Noncurrent finance lease liabilities (included in Long-term debt)	$ 92	$ 63
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term Debt, Excluding Current Maturities	Long-term Debt, Excluding Current Maturities
Total finance lease liabilities	$ 108	$ 70
Finance Lease, Liability, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtCurrent us-gaap:LongTermDebtNoncurrent	us-gaap:LongTermDebtCurrent us-gaap:LongTermDebtNoncurrent
Weighted-average remaining lease term (in years):
Operating leases weighted-average remaining lease term (in years)	4 years 9 months 18 days	3 years 7 months 6 days
Finance leases weighted-average remaining lease term (in years)	6 years 10 months 24 days	7 years 4 months 24 days
Weighted-average discount rate:
Operating leases (as a percent)	3.69%	4.17%
Finance leases (as a percent)	2.73%	3.57%