Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	$ 710	$ 571
Other revenues	26	23
Operating revenues and other	736	594
CNA Financial | Non-insurance warranty
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	407	407
Boardwalk Pipelines | Transportation and storage of natural gas and NGLs and other services
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	501	386
Loews Hotels & Co | Lodging and related services
Disaggregation of Revenues [Abstract]
Revenues from contracts with customers	$ 209	$ 185