Leases - Lease Maturity (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Operating Leases
Remainder of 2019	$ 28
2020	100
2021	61
2022	44
2023	29
2024 and thereafter	85
Total Lease Liabilities, Undiscounted	347
Less: Imputed Interest	41
Total Lease Liabilities	306
Finance Leases
Remainder of 2019	13
2020	49
2021	35
2022	25
2023	22
2024 and Thereafter	106
Total Lease Liabilities, Undiscounted	250
Less: Imputed Interest	44
Total Lease Liabilities	206
Total
Remainder of 2019	41
2019		$ 143
2020	149	120
2021	96	90
2022	69	84
2023	51	70
2024 and Thereafter	191	280
Total Lease Liabilities, Undiscounted	597	787
Liabilities, Undiscounted Excess Amount	85
Lease Liability	512
Operating lease liability, current	97	0
Finance lease liability, current	$ 42	41
Operating Leases
2019		91
2020		74
2021		59
2022		62
2023		50
2024 and Thereafter		176
Total Lease Liabilities, Undiscounted		512
Finance Leases
2019		52
2020		46
2021		31
2022		22
2023		20
2024 and Thereafter		104
Total Lease Liabilities, Undiscounted		$ 275