Employee Benefits - Cash Flows (Details) $ in Millions	Dec. 31, 2020 USD ($)
Medicare subsidy
2021 (less than)	$ (1)
2022 (less than)	(1)
2023 (less than)	(1)
2024 (less than)	(1)
2025 (less than)	(1)
2026-2030 (less than)	(1)
Retirement Plans
Information about the expected cash flows for retirement and post-retirement plans and impact of the Medicare subsidy
2021	66
2022	69
2023	72
2024	75
2025	78
2026-2030	433
Postretirement Plans
Information about the expected cash flows for retirement and post-retirement plans and impact of the Medicare subsidy
2021	4
2022	4
2023	4
2024	3
2025	3
2026-2030	10
Gross payments
2021	6
2022	5
2023	5
2024	4
2025	4
2026-2030	16
Retiree contributions
2021	(2)
2022	(1)
2023	(1)
2024	(1)
2025	(1)
2026-2030	$ (6)

Defined benefit plan expected future benefit payments gross in five fiscal years thereafter.

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