Leases (Maturity Analysis For Operating and Finance Lease) (Details) $ in Millions	Mar. 31, 2019 USD ($)
Operating Lease Liabilities, Payments Due [Abstract]
2019 (remaining months)	$ 39
2020	42
2021	38
2022	35
2023	32
Thereafter	96
Total lease payments	282
Less: imputed interest	(74)
Present value of lease liabilities	208
Finance Lease Liabilities, Payments, Due [Abstract]
2019 (remaining months)	35
2020	36
2021	30
2022	25
2023	21
Thereafter	115
Total lease payments	262
Less: imputed interest	(77)
Present value of lease liabilities	$ 185