Investments (Current And Long-Term Investments, Available-For-Sale) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Investment [Line Items]
Fixed Maturity Securities, Allowance for Credit Loss	$ (9)	$ (6)
Fixed Maturity Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	29,015	26,257
Gross Unrealized Gains	76	830
Gross Unrealized Losses	(2,378)	(182)
Fixed Maturity Securities, Allowance for Credit Loss	(9)	(6)
Estimated Fair Value	26,704	26,899
Fixed Maturity Securities [Member] \| United States Government Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	1,502	1,443
Gross Unrealized Gains	2	7
Gross Unrealized Losses	(103)	(18)
Fixed Maturity Securities, Allowance for Credit Loss	0	0
Estimated Fair Value	1,401	1,432
Fixed Maturity Securities [Member] \| Government Sponsored Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	82	65
Gross Unrealized Gains	1	4
Gross Unrealized Losses	(5)	(1)
Fixed Maturity Securities, Allowance for Credit Loss	0	0
Estimated Fair Value	78	68
Fixed Maturity Securities [Member] \| Foreign Government Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	321	353
Gross Unrealized Gains	1	7
Gross Unrealized Losses	(46)	(13)
Fixed Maturity Securities, Allowance for Credit Loss	(2)	0
Estimated Fair Value	274	347
Fixed Maturity Securities [Member] \| States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Investment [Line Items]
Cost or Amortized Cost	4,389	5,321
Gross Unrealized Gains	19	310
Gross Unrealized Losses	(265)	(10)
Fixed Maturity Securities, Allowance for Credit Loss	0	0
Estimated Fair Value	4,143	5,621
Fixed Maturity Securities [Member] \| Corporate Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	13,721	12,044
Gross Unrealized Gains	31	401
Gross Unrealized Losses	(1,218)	(78)
Fixed Maturity Securities, Allowance for Credit Loss	(5)	(4)
Estimated Fair Value	12,529	12,363
Fixed Maturity Securities [Member] \| Residential Mortgage-Backed Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	2,978	2,492
Gross Unrealized Gains	9	48
Gross Unrealized Losses	(324)	(22)
Fixed Maturity Securities, Allowance for Credit Loss	0	0
Estimated Fair Value	2,663	2,518
Fixed Maturity Securities [Member] \| Commercial Mortgage-Backed Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	2,055	1,632
Gross Unrealized Gains	1	29
Gross Unrealized Losses	(176)	(16)
Fixed Maturity Securities, Allowance for Credit Loss	(2)	(2)
Estimated Fair Value	1,878	1,643
Fixed Maturity Securities [Member] \| Other Asset-Backed Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	3,967	2,907
Gross Unrealized Gains	12	24
Gross Unrealized Losses	(241)	(24)
Fixed Maturity Securities, Allowance for Credit Loss	0	0
Estimated Fair Value	$ 3,738	$ 2,907

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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