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- Definition

Defined Contribution Plan, Vesting Period

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defined benefit plan covered employee percentage

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Purchase of Medical Coverage through Medicare Exchange Participant, Age

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Amount of actuarial present value of benefits attributed to employee service rendered, excluding assumptions about future compensation level.

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Amount of cost (credit) included in accumulated other comprehensive (income) loss expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position.

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Amount included in accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan expected to be recognized in net periodic benefit (cost) credit for fiscal year following most recent annual statement of financial position.

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Amount included in accumulated other comprehensive (income) loss for prior service cost (credit) expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position.

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Amount of contributions expected to be received by defined benefit plan from employer in next fiscal year following latest fiscal year.

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Assumed rate, for next fiscal year, based on annual change in cost of health care cost benefits used to measure expected cost of benefits covered by defined benefit postretirement plan. Factors include, but are not limited to, estimate of health care inflation, change in health care utilization or delivery pattern, technological advances, and change in health status of participant. Excludes factors for change in composition of plan population by age and dependency status.

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- Definition

Amount of accumulated benefit obligation for defined benefit plan with accumulated benefit obligation in excess of plan assets.

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Amount of plan asset for defined benefit plan with accumulated benefit obligation in excess of plan assets.

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

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Ultimate trend rate for health care cost for defined benefit postretirement plan.

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Amount of cost for defined contribution plan.

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Percentage of employees' gross pay for which the employer contributes a matching contribution to a defined contribution plan.

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Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

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Share-based Compensation and Employee Benefits - Pensions and Other Postretirement Benefit Plans - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Components of Accumulated Other Comprehensive Income/Loss
Expected amortization in next year	$ 25
Expected amortization in next year, unrecognized net actuarial loss	27
Expected amortization in next year, unrecognized prior service credit	$ 2
Savings plan - defined contribution plan
Savings Plan
Percentage of eligible compensation contributed	5.00%
Plan vesting period	2 years
Plan cost	$ 50	$ 48	$ 47
Pension Benefits
Pension Plans and Other Postretirement Benefit Plans
Percentage of employees covered	100.00%
Vesting period	3 years
Components of Accumulated Other Comprehensive Income/Loss
Accumulated benefit obligation	$ 2,659	2,535
Expected Payment of Future Benefits and Employer Contributions
Expected employer contributions in next year	$ 71
Pension Benefits \| Minimum \| Equities
Plan Assets
Target allocation percentage	34.00%
Pension Benefits \| Minimum \| Fixed Income Securities
Plan Assets
Target allocation percentage	37.00%
Pension Benefits \| Minimum \| Cash
Plan Assets
Target allocation percentage	0.00%
Pension Benefits \| Minimum \| Alternative Investments
Plan Assets
Target allocation percentage	0.00%
Pension Benefits \| Minimum \| Company Securities
Plan Assets
Target allocation percentage	0.00%
Pension Benefits \| Maximum \| Equities
Plan Assets
Target allocation percentage	59.00%
Pension Benefits \| Maximum \| Fixed Income Securities
Plan Assets
Target allocation percentage	57.00%
Pension Benefits \| Maximum \| Cash
Plan Assets
Target allocation percentage	5.00%
Pension Benefits \| Maximum \| Alternative Investments
Plan Assets
Target allocation percentage	2.00%
Pension Benefits \| Maximum \| Company Securities
Plan Assets
Target allocation percentage	10.00%
OPEB
Pension Plans and Other Postretirement Benefit Plans
Medicare participation, age	65
Components of Accumulated Other Comprehensive Income/Loss
Accumulated benefit obligation whose accumulated benefit obligations exceeded the fair value of plan assets	$ 288	293
Accumulated benefit obligation whose accumulated benefit obligations exceeded the fair value of plan assets, fair value of plan assets	57	$ 70
Expected Payment of Future Benefits and Employer Contributions
Expected employer contributions in next year	$ 7
Actuarial Assumptions and Sensitivity Analysis
Weighted-average annual rate of increase in the per capita cost of covered health care benefits	8.38%
Ultimate health care cost trend rate	4.54%
OPEB \| Minimum \| Equities
Plan Assets
Target allocation percentage	45.00%
OPEB \| Minimum \| Fixed Income Securities
Plan Assets
Target allocation percentage	25.00%
OPEB \| Minimum \| Cash
Plan Assets
Target allocation percentage	0.00%
OPEB \| Maximum \| Equities
Plan Assets
Target allocation percentage	68.00%
OPEB \| Maximum \| Fixed Income Securities
Plan Assets
Target allocation percentage	50.00%
OPEB \| Maximum \| Cash
Plan Assets
Target allocation percentage	22.00%
Accounting Standards Update 2017-07 \| General and Administrative
Pension and Other Postretirement Benefit Plans
Impact of adoption of ASUs			(15)
Accounting Standards Update 2017-07 \| Other, Net
Pension and Other Postretirement Benefit Plans
Impact of adoption of ASUs			$ 15