Income Taxes (Geographic Sources) (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Geographic sources of pretax income
United States	$ 1,685	$ 2,045	$ 2,263
Foreign	146	187	221
Income from continuing operations before income tax provision	$ 1,831	$ 2,232	$ 2,484