Pension and Other Postemployment Benefits (Details 9) $ in Millions	Dec. 31, 2016 USD ($)
Pension
Estimated Future Benefit Payments
2017	$ 505
2018	523
2019	534
2020	552
2021	566
2022-2026	2,999
OPEB
Estimated Future Benefit Payments
2017	52
2018	52
2019	53
2020	53
2021	53
2022-2026	251
Subsidy Receipts
2017	(3)
2018	(3)
2019	(3)
2020	(3)
2021	(3)
Years 2022-2026	$ (7)

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