Pension and Other Postretirement Benefit Plans - Amounts Recognized in our Consolidated Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Accounts payable and other	$ (14)	$ (14)
Pension and OPEB obligations	(1,151)	(1,562)
Pension Plans
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Other assets	2	0
Accounts payable and other	(3)	(3)
Pension and OPEB obligations	(1,040)	(1,437)
Net obligations recognized	(1,041)	(1,440)
OPEB Plans
Pension Plans, Postretirement and Other Employee Benefits [Line Items]
Other assets	0	0
Accounts payable and other	(11)	(11)
Pension and OPEB obligations	(111)	(125)
Net obligations recognized	$ (122)	$ (136)