Leases - Schedule of Operating and Finance Lease Maturities (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Leases
Remainder of 2019	$ 166
2020	167
2021	110
2022	78
2023	53
Thereafter	170
Total lease payments	744
Less: Interest	(62)
Present value of lease liabilities	682
Finance Leases
Remainder of 2019	9
2020	12
2021	1
2022	1
2023	1
Thereafter	0
Total lease payments	24
Less: Interest	(1)
Present value of lease liabilities	23
Total
Remainder of 2019	175
2020	179
2021	111
2022	79
2023	54
Thereafter	170
Total lease payments	768
Less: Interest	(63)
Present value of lease liabilities	$ 705
Weighted average lease term, operating lease	5 years 8 months 12 days
Weighted average discount rate, operating lease	3.12%
Weighted average lease term, finance lease	2 years 6 months
Weighted average discount rate, finance lease	2.95%