Debt (Debt Maturities) (Details) $ in Millions	Dec. 31, 2019 USD ($)	[1]
Debt [Abstract]
Long-term debt, due 2020	$ 11
Long-term debt, due 2021	77
Long-term debt, due 2022	390
Long-term debt, due 2023	432
Long-term debt, due 2024	316
Long-term debt, due Thereafter	$ 6,569

[1] Excludes interest rate swap gains, bond discounts and deferred expenses.