Variable Interest Entities (Narrative) (Details) - USD ($)	6 Months Ended		12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Variable Interest Entity [Line Items]
Gains (losses) for consolidated variable interest entities	$ 0		$ 0
Carrying amount of other investments	2,845,000,000		2,267,000,000
Maximum [Member]
Variable Interest Entity [Line Items]
Income Tax Credits And Other Tax Benefits From Qualified Affordable Housing Projects	1,000,000	$ 1,000,000
Limited Partnerships and Limited Liability Companies [Member]
Variable Interest Entity [Line Items]
Carrying amount of other investments	1,900,000,000		1,700,000,000
Carrying Amount Of Investments In Qualified Affordable Housing Projects	$ 16,000,000		$ 20,000,000