Pension and Other Postretirement Benefits - Schedule of Pension Plan Benefit Obligations (Details) - Pension benefits paid - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Projected benefit obligation	$ 2,296	$ 2,713	$ 7,249
Accumulated benefit obligation	2,293	2,707
The aggregate projected benefit obligation and fair value of plan assets for pension plans with projected benefit obligations in excess of plan assets were as follows:
Projected benefit obligation	1,982	2,364
Fair value of plan assets	1,193	1,364
The aggregate accumulated benefit obligation and fair value of plan assets for pension plans with accumulated benefit obligations in excess of plan assets were as follows:
Accumulated benefit obligation	1,981	2,359
Fair value of plan assets	$ 1,193	$ 1,364