Defined Benefit Plan, Number Of Investment Firms

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- Definition

The fair value of trust-owned life insurance related to postretirement benefit plan assets as of the reporting period.

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- Definition

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

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- Definition

Weighted average rate of return on plan assets, reflecting average rate of earnings expected on existing plan assets and expected contributions, used to determine net periodic benefit cost of defined benefit plan.

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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- Definition

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 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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- Definition

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

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- Definition

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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- Definition

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

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- Definition

Percentage of investment to total investment within defined benefit plan asset category.

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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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- Definition

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

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- Definition

Amount of cost for defined contribution plan.

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- Definition

Amount of cost for employer contribution to multiemployer plan. Multiemployer plan includes, but is not limited to, pension plan determined to be individually significant and insignificant and other postretirement benefit plan.

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Pensions and Other Postretirement Benefits - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) investment_firm	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan's accumulated benefit obligation	$ 2,600	$ 2,300
Unfunded pension plans projected benefit obligation	359	320
Unfunded pension plans accumulated benefit obligations	$ 330	292
Number of investment firms \| investment_firm	11
Multiemployer plan, contributions by employer	$ 22	31	$ 35
Defined contribution plan, cost	21	22	$ 23
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Estimated net loss for defined pension plans amortized from AOCI into net periodic cost	$ 66
Assumed increases in per capita cost of covered health care benefits	6.00%
Ultimate health care cost trend rate	5.00%
Pension plan assets target allocation for equity	75.00%
Assumed rate of return on pension plan assets	8.00%
Expected contribution for the next fiscal year	$ 19
OPEB
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, future amortization of prior service cost (credit)	23
Expected contribution for the next fiscal year	36
Fair Value Inputs Level 2
Defined Benefit Plan Disclosure [Line Items]
Trust-owned life insurance fair value	$ 165	$ 170
Debt securities
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation, by asset category	32.00%	33.00%
Defined Benefit Plan, Equity Securities \| OPEB
Defined Benefit Plan Disclosure [Line Items]
Weighted average asset allocation, by asset category	68.00%	67.00%
Minimum
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets target allocation for equity	50.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets target allocation for equity	75.00%