Retirement Plans (Changes in Level 3 Retirement Plan Assets) (Details) - Significant Unobservable Inputs (Level 3) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	$ 318	$ 282
Unrealized gains, net	6	33
Realized losses, net		(1)
Purchases, sales and settlements, net	(3)	4
Transfers out of Level 3	(115)
Fair value of assets at end of year	206	318
Insurance Deposits Contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	157	137
Unrealized gains, net	9	18
Realized losses, net		0
Purchases, sales and settlements, net	(3)	2
Transfers out of Level 3	0
Fair value of assets at end of year	163	157
Retirement annuity contracts
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	38	35
Unrealized gains, net	(3)	3
Realized losses, net		0
Purchases, sales and settlements, net	0	0
Transfers out of Level 3	0
Fair value of assets at end of year	35	38
Private equity investments
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	33	26
Unrealized gains, net	0	5
Realized losses, net		0
Purchases, sales and settlements, net	0	2
Transfers out of Level 3	(33)
Fair value of assets at end of year	0	33
Real Estate Funds
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value of assets at beginning of year	90	84
Unrealized gains, net	0	7
Realized losses, net		(1)
Purchases, sales and settlements, net	0	0
Transfers out of Level 3	(82)
Fair value of assets at end of year	$ 8	$ 90

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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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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

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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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