Employee Benefit Plans (Significant Unobservable Inputs) (Details) - Pension Benefits - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	$ 9,688	$ 9,009
Purchases, sales, issuances and settlements, net	(5)	(30)
Estimated fair value of plan assets at December 31,	8,948	9,688
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,	3,834
Estimated fair value of plan assets at December 31,	3,351	3,834
Foreign government
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	1,037
Estimated fair value of plan assets at December 31,	837	1,037
Other (1)
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	405
Estimated fair value of plan assets at December 31,	801	405
Equity securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	977
Estimated fair value of plan assets at December 31,	901	977
Other investments
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	785
Estimated fair value of plan assets at December 31,	708	785
Derivative assets
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	35
Estimated fair value of plan assets at December 31,	38	35
Level 3
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	636
Estimated fair value of plan assets at December 31,	691	636
Level 3 \| 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,	1	0
Realized gains (losses)	0	(10)
Unrealized gains (losses)	0	10
Purchases, sales, issuances and settlements, net	0	0
Transfers into and/or out of Level 3	0	1
Estimated fair value of plan assets at December 31,	1	1
Level 3 \| 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 (1)
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	10	9
Realized gains (losses)	0	0
Unrealized gains (losses)	0	0
Purchases, sales, issuances and settlements, net	(3)	8
Transfers into and/or out of Level 3	(6)	(7)
Estimated fair value of plan assets at December 31,	1	10
Level 3 \| Equity securities
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	3	0
Realized gains (losses)	0	2
Unrealized gains (losses)	0	0
Purchases, sales, issuances and settlements, net	0	(4)
Transfers into and/or out of Level 3	(3)	5
Estimated fair value of plan assets at December 31,	0	3
Level 3 \| Other investments
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	622	637
Realized gains (losses)	0	0
Unrealized gains (losses)	23	(12)
Purchases, sales, issuances and settlements, net	43	0
Transfers into and/or out of Level 3	0	(3)
Estimated fair value of plan assets at December 31,	688	622
Level 3 \| Derivative assets
Rollforward fair value measurement using significant unobservable inputs (level 3) [Roll Forward]
Estimated fair value of plan assets at January 1,	0	65
Realized gains (losses)	0	(22)
Unrealized gains (losses)	0	6
Purchases, sales, issuances and settlements, net	0	(48)
Transfers into and/or out of Level 3	1	(1)
Estimated fair value of plan assets at December 31,	$ 1	$ 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

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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

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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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