Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2025	Mar. 31, 2024
Disaggregation of Revenues [Abstract]
Total revenues from contracts with customers	$ 846	$ 710
Other revenues	26	26
Operating revenues and other	872	736
CNA Financial \| Non-insurance warranty
Disaggregation of Revenues [Abstract]
Total revenues from contracts with customers	397	407
Boardwalk Pipelines \| Transportation and storage of natural gas and NGLs and other services
Disaggregation of Revenues [Abstract]
Total revenues from contracts with customers	609	501
Loews Hotels & Co \| Lodging and related services
Disaggregation of Revenues [Abstract]
Total revenues from contracts with customers	$ 237	$ 209

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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