Other Comprehensive Income Phantom (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss) before Reclassifications, Tax	$ (8)	$ (2)	$ 0
Income Tax Expense (Benefit)	128	181	$ 542
Reclassification out of Accumulated Other Comprehensive Income | Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss) before Reclassifications, Tax	(8)	(2)
Income Tax Expense (Benefit)	1	1
Reclassification from AOCI, Current Period, Tax	0	0
Reclassification out of Accumulated Other Comprehensive Income | Defined Benefit Pension and Postretirement Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive Income (Loss) before Reclassifications, Tax	0	(2)
Income Tax Expense (Benefit)	0	0
Reclassification from AOCI, Current Period, Tax	$ 1	$ 3