Leases - Maturities (Details) $ in Millions	Sep. 30, 2019 USD ($)
Maturities of operating lease liabilities [Abstract]
2019	$ 47
2020	177
2021	149
2022	129
2023	88
Thereafter	137
Total operating lease payments	727
Less: imputed interest, operating leases	70
Total operating lease liabilities	657
Maturities of finance lease liabilities [Abstract]
2019	9
2020	25
2021	17
2022	16
2023	8
Thereafter	22
Total finance lease payments	97
Less: imputed interest, finance leases	10
Total finance lease liabilities	$ 87