Leasing - Present Value of Lease Liabilities (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Leases
2019	$ 102
2020	103
2021	79
2022	59
2023	44
Thereafter	310
Total lease payments	697
Less: Amount representing interest	189
Present value of lease liabilities	508
Finance Leases
2019	1
2020	1
2021	0
2023	0
2024	0
Thereafter	0
Total lease payments	2
Less: Amount representing interest	0
Present value of lease liabilities	$ 2