Comprehensive Loss (Narrative) (Details) - Pension Settlement Cost [Member] - Pension Benefits [Member] - Reclassification out of Accumulated Other Comprehensive Income [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassifications, pretax	$ (159)	$ (57)	$ (41)
Reclassifications, net of tax	$ 122	$ 43	$ 31