Segment Information (Reconciliation Of Reportable Segments Operating Revenues To Total Revenues Reported In The Consolidated Statements Of Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting [Abstract]
Reportable segments operating revenues	$ 26,444	$ 22,980	$ 76,009	$ 68,037
Net investment income	242	250	737	708
Net realized gains on financial instruments	1	27	90	5
Other-than-temporary impairment losses recognized in income	(13)	(6)	(30)	(18)
Total revenues	$ 26,674	$ 23,251	$ 76,806	$ 68,732