Postretirement Plans - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) defined_benefit_plan	Dec. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Dec. 08, 2025 defined_benefit_plan medical_plan
Defined Benefit Plan Disclosure [Line Items]
Number of defined benefit plan | defined_benefit_plan	7			3
Number of post-retirement medical plan | medical_plan				2
Amount by which fair value of plan assets exceeds market-related value of plan assets (MRVA)	$ (1,398)
Derivative net notional amount for fixed income as percentage of total plan assets	41.60%	42.00%
Derivative net notional amount for global equity, currency overlay and commodities as a percentage of total plan assets	(0.60%)	0.80%
Defined contribution plan, cost	$ 1,602	$ 1,670	$ 1,564
Pension
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation (ABO) for all pension plans	$ 50,792	$ 49,889
Defined benefit plan, actual plan asset allocations	100.00%	100.00%
Pension | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations	59.00%	59.00%
Pension | Equity securities:
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations	20.00%	19.00%
Pension | Corporate | Fixed income | Level 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets Level 3 reconciliation, increase (decrease) for actual return (loss) on plan assets still held	$ 7	$ (7)
Pension | Mortgage backed and asset backed | Fixed income | Level 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets Level 3 reconciliation, increase (decrease) for actual return (loss) on plan assets still held	1	$ 1
Pension | Asset backed private loans | Fixed income | Level 3
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets Level 3 reconciliation, increase (decrease) for actual return (loss) on plan assets still held	$ 46
Other Postretirement Benefits | Fixed income
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations	40.00%
Other Postretirement Benefits | Equity securities:
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations	60.00%