Goodwill and Other Intangible Assets, Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 785	$ 767
Acquisition		18
Deconsolidation of Altium Packaging (see Note 2)	(436)
Goodwill, ending balance	349	785
Non-insurance warranty – CNA Financial
Goodwill [Roll Forward]
Goodwill, beginning balance	112	112
Goodwill, ending balance	112	112
Transportation and storage of natural gas and NGLs and other services – Boardwalk Pipelines
Goodwill [Roll Forward]
Goodwill, beginning balance	237	237
Goodwill, ending balance	237	237
Rigid plastic packaging and recycled resin - Corporate
Goodwill [Roll Forward]
Goodwill, beginning balance	436	418
Acquisition		18
Deconsolidation of Altium Packaging (see Note 2)	(436)
Goodwill, ending balance	$ 0	$ 436