Investments (Current And Long-Term Investments, Available-For-Sale) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Investment [Line Items]
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	$ (6)	$ (7)
Fixed Maturity Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	26,257	22,754
Gross Unrealized Gains	830	1,316
Gross Unrealized Losses	(182)	(68)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	(6)	(7)	$ 0
Estimated Fair Value	26,899	23,995
Fixed Maturity Securities [Member] \| United States Government Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	1,443	765
Gross Unrealized Gains	7	11
Gross Unrealized Losses	(18)	(2)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	0	0
Estimated Fair Value	1,432	774
Fixed Maturity Securities [Member] \| Government Sponsored Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	65	63
Gross Unrealized Gains	4	6
Gross Unrealized Losses	(1)	0
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	0	0
Estimated Fair Value	68	69
Fixed Maturity Securities [Member] \| Foreign Government Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	353	290
Gross Unrealized Gains	7	17
Gross Unrealized Losses	(13)	(2)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	0	0	0
Estimated Fair Value	347	305
Fixed Maturity Securities [Member] \| States, Municipalities And Political Subdivisions, Tax-Exempt [Member]
Investment [Line Items]
Cost or Amortized Cost	5,321	5,185
Gross Unrealized Gains	310	395
Gross Unrealized Losses	(10)	(1)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	0	0
Estimated Fair Value	5,621	5,579
Fixed Maturity Securities [Member] \| Corporate Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	12,044	10,233
Gross Unrealized Gains	401	697
Gross Unrealized Losses	(78)	(31)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	(4)	(7)	$ 0
Estimated Fair Value	12,363	10,892
Fixed Maturity Securities [Member] \| Residential Mortgage-Backed Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	4,059	4,208
Gross Unrealized Gains	75	154
Gross Unrealized Losses	(35)	(17)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	(2)	0
Estimated Fair Value	4,097	4,345
Fixed Maturity Securities [Member] \| Commercial Mortgage-Backed Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	65	73
Gross Unrealized Gains	2	3
Gross Unrealized Losses	(3)	(4)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	0	0
Estimated Fair Value	64	72
Fixed Maturity Securities [Member] \| Other Securities [Member]
Investment [Line Items]
Cost or Amortized Cost	2,907	1,937
Gross Unrealized Gains	24	33
Gross Unrealized Losses	(24)	(11)
Fixed Maturity Securities, Available-for-sale, Allowance for Credit Loss	0	0
Estimated Fair Value	$ 2,907	$ 1,959

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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