Variable Interest Entities (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Variable Interest Entity [Line Items]
Gains (losses) for consolidated variable interest entities	$ 0	$ 0	$ 0	$ 0
Carrying amount of other investments	4,069		4,069		$ 3,984
Income Tax Credits And Other Tax Benefits From Qualified Affordable Housing Projects	1		1
Income tax expense				$ (4)
Maximum [Member]
Variable Interest Entity [Line Items]
Income tax expense		$ 1
Limited Partnerships and Limited Liability Companies [Member]
Variable Interest Entity [Line Items]
Carrying amount of other investments	2,700		2,700		2,100
Carrying Amount Of Investments In Qualified Affordable Housing Projects	$ 5		$ 5		$ 7