Leases - Maturities of Lease Liabilities (Details) $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($)
Operating Leases
2019	$ 8
2020	42
2021	40
2022	39
2023	35
2024	30
Thereafter	108
Total lease payments	302
Less imputed interest	(56)
Total net present value	246
Finance Leases
2019	12
2020	19
2021	17
2022	15
2023	8
2024	4
Thereafter	12
Total lease payments	87
Less imputed interest	(24)
Total net present value	63
Total
2019	20
2020	61
2021	57
2022	54
2023	43
2024	34
Thereafter	120
Total lease payments	389
Less imputed interest	(80)
Total leased liabilities	309
Sublease receipts	$ 13
Term of sublease income	13 years