Variable Interest Entities (Narrative) (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Variable Interest Entity [Line Items]
Gains (losses) for consolidated variable interest entities	$ 0		$ 0
Carrying amount of other investments	4,574		2,994
Maximum [Member]
Variable Interest Entity [Line Items]
Income Tax Credits And Other Tax Benefits From Qualified Affordable Housing Projects	1	$ 1
Limited Partnerships and Limited Liability Companies [Member]
Variable Interest Entity [Line Items]
Carrying amount of other investments	1,800		1,900
Carrying Amount Of Investments In Qualified Affordable Housing Projects	$ 10		$ 13