Income Taxes (Schedule of Deferred Tax Assets and Liabilities Footnotes) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Abstract]
Valuation allowance, deferred tax asset, increase (decrease), amount		$ (6)	$ 250
Foreign deferred tax valuation allowance	$ 203	$ 0	$ 203	$ 0