Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated Other Comprehensive Income (Loss), Net of Tax (Reclassifications out of AOCI) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	$ (49)	$ (15)	$ 12
Tax (Expense) Benefit	19	(4)	8
After-Tax Amount	(30)	(11)	4
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	(5)	(4)	(14)
Tax (Expense) Benefit	2	(1)	(4)
After-Tax Amount	(3)	(3)	(10)
Pension and OPEB Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	(1)	(20)	(16)
Tax (Expense) Benefit	0	(6)	(4)
After-Tax Amount	(1)	(14)	(12)
Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	(43)	9	42
Tax (Expense) Benefit	17	3	16
After-Tax Amount	(26)	6	26
Interest Expense | Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	(5)	(4)	(14)
Tax (Expense) Benefit	2	(1)	(4)
After-Tax Amount	(3)	(3)	(10)
Amortization of Prior Service (Cost) Credit | Pension and OPEB Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	21	(21)	(24)
Tax (Expense) Benefit	(6)	(6)	(7)
After-Tax Amount	15	(15)	(17)
Amortization of Actuarial Loss | Pension and OPEB Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	(22)	41	40
Tax (Expense) Benefit	6	12	11
After-Tax Amount	(16)	29	29
Net Gains (Losses) on Trust Investments | Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-Tax Amount	(43)	9	42
Tax (Expense) Benefit	17	3	16
After-Tax Amount	$ (26)	$ 6	$ 26