Employee Benefit Plans (Significant Unobservable Inputs) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Pension Benefits
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	$ 8,294	$ 10,971
Purchases, sales, issuances and settlements, net	(35)	(38)
Estimated fair value of plan assets at December 31,	8,270	8,294
Pension Benefits \| Foreign government
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	769
Estimated fair value of plan assets at December 31,	810	769
Pension Benefits \| Other (1)
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	693
Estimated fair value of plan assets at December 31,	699	693
Pension Benefits \| Equity Securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	570
Estimated fair value of plan assets at December 31,	610	570
Pension Benefits \| Corporate fixed maturity securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	3,001
Estimated fair value of plan assets at December 31,	3,083	3,001
Other Postretirement Benefits
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	1,303	1,443
Purchases, sales, issuances and settlements, net	0	0
Estimated fair value of plan assets at December 31,	1,334	1,303
Other Postretirement Benefits \| Foreign government
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	61
Estimated fair value of plan assets at December 31,	46	61
Other Postretirement Benefits \| Other (1)
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	44
Estimated fair value of plan assets at December 31,	37	44
Other Postretirement Benefits \| Equity Securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	47
Estimated fair value of plan assets at December 31,	59	47
Other Postretirement Benefits \| Corporate fixed maturity securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	205
Estimated fair value of plan assets at December 31,	167	205
Level 3 \| Pension Benefits
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	920
Estimated fair value of plan assets at December 31,	904	920
Level 3 \| Pension Benefits \| Foreign government
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	0	1
Realized gains (losses)	0	0
Unrealized gains (losses)	0	0
Purchases, sales, issuances and settlements, net	0	0
Transfers into and/or out of Level 3	2	(1)
Estimated fair value of plan assets at December 31,	2	0
Level 3 \| Pension Benefits \| Other (1)
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	3	1
Realized gains (losses)	0	0
Unrealized gains (losses)	0	0
Purchases, sales, issuances and settlements, net	0	3
Transfers into and/or out of Level 3	5	(1)
Estimated fair value of plan assets at December 31,	8	3
Level 3 \| Pension Benefits \| Equity Securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	3	11
Realized gains (losses)	0	0
Unrealized gains (losses)	1	0
Purchases, sales, issuances and settlements, net	8	(8)
Transfers into and/or out of Level 3	0	0
Estimated fair value of plan assets at December 31,	12	3
Level 3 \| Pension Benefits \| Other investments
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	855	954
Realized gains (losses)	(1)	0
Unrealized gains (losses)	(51)	54
Purchases, sales, issuances and settlements, net	25	(153)
Transfers into and/or out of Level 3	0	0
Estimated fair value of plan assets at December 31,	828	855
Level 3 \| Pension Benefits \| Corporate fixed maturity securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	55	0
Realized gains (losses)	0	0
Unrealized gains (losses)	1	(1)
Purchases, sales, issuances and settlements, net	2	56
Transfers into and/or out of Level 3	(4)	0
Estimated fair value of plan assets at December 31,	54	55
Level 3 \| Pension Benefits \| Derivative Financial Instruments, Assets
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	4	0
Realized gains (losses)	0	0
Unrealized gains (losses)	(1)	1
Purchases, sales, issuances and settlements, net	(3)	3
Transfers into and/or out of Level 3	0	0
Estimated fair value of plan assets at December 31,	0	4
Level 3 \| Other Postretirement Benefits
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	0
Estimated fair value of plan assets at December 31,	0	0
Level 3 \| Other Postretirement Benefits \| Foreign government
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	0
Estimated fair value of plan assets at December 31,	0	0
Level 3 \| Other Postretirement Benefits \| Other (1)
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	0
Estimated fair value of plan assets at December 31,	0	0
Level 3 \| Other Postretirement Benefits \| Equity Securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	0
Estimated fair value of plan assets at December 31,	0	0
Level 3 \| Other Postretirement Benefits \| Corporate fixed maturity securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	0
Estimated fair value of plan assets at December 31,	$ 0	$ 0

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets sold.

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- Definition

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan from actual return (loss) on assets still held.

+ References

+ Details

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition

Amount, measured using unobservable input, of increase (decrease) in plan asset of defined benefit plan from purchase, sale and settlement of trade associated with underlying investment.

+ References

+ Details

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- Definition

Amount, measured using unobservable inputs, of increase (decrease) in plan assets of defined benefit plan, for assets transferred into (out of) Level 3 of fair value hierarchy. Includes, but is not limited to, transfer due to change in observability of significant inputs.

+ References

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