Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	$ 500	$ 425	$ 1,520	$ 1,518
Other revenues	33	25	87	62
Operating revenues and other	533	450	1,607	1,580
Non-insurance warranty – CNA Financial | CNA Financial
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	399	357	1,173	1,054
Transportation and storage of natural gas and NGLs and other services – Boardwalk Pipelines | Transportation and storage of natural gas and NGLs and other services – Boardwalk Pipelines
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	329	296	1,013	959
Lodging and related services – Loews Hotels & Co | Lodging and related services – Loews Hotels & Co
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	171	129	507	279
Rigid plastic packaging and recycled resin - Corporate | Rigid plastic packaging and recycled resin - Corporate
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers				$ 280