Income Taxes (Summary of Valuation Allowance) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Deferred Tax Assets, Valuation Allowance [Roll Forward]
Balance at beginning of year	$ 3,097	$ 2,817	$ 2,324
Additions to valuation allowance charged to income tax expense	429	401	692
Reductions to valuation allowance credited to income tax benefit	(730)	(118)	(200)
Foreign currency translation	4	(3)	1
Balance at end of year	$ 2,800	$ 3,097	$ 2,817