Leases (Payment Schedule for Operating Lease Obligations) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2019
Leases [Abstract]
2021	$ 107
2022	63
2023	26
2024	8
2025	5
Thereafter	14
Total lease payments	223
Less present value discount	(13)
Present value of lease liabilities	210	$ 306	$ 325
2021	33
2022	34
2023	35
2024	35
2025	36
Thereafter	564
Total lease payments	737
Less present value discount	(181)
Present value of lease liabilities	$ 556	$ 572	$ 0