Revenue from Contracts with Customers - Disaggregation of Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenues
Revenues from contracts with customers	$ 2,087	$ 2,005	$ 2,820
Other revenues	113	128	113
Operating revenues and other	2,200	2,133	2,933
Deferred Revenue
Deferred revenue	4,714	4,503
Revenue recognized	1,400	1,200
Contract Costs
Capitalized contract cost	3,671	3,476
Amortization of contract costs	1,200	1,100
Adjustments to deferred costs	0	0
Receivables
Receivables from Contracts with Customers
Receivables from contracts with customers	168	145
Other liabilities
Deferred Revenue
Deferred revenue	4,800	4,600
Deferred Non-insurance Warranty Acquisition Expenses
Contract Costs
Capitalized contract cost	3,700	3,500
Operating Segments | CNA Financial
Disaggregation of Revenues
Operating revenues and other	32	24	26
Operating Segments | CNA Financial | Non-insurance warranty – CNA Financial
Disaggregation of Revenues
Revenues from contracts with customers	1,574	1,430	1,252
Operating Segments | Boardwalk Pipelines
Disaggregation of Revenues
Operating revenues and other	1,443	1,349	1,302
Operating Segments | Boardwalk Pipelines | Transportation and storage of natural gas and NGLs and other services – Boardwalk Pipelines
Disaggregation of Revenues
Revenues from contracts with customers	1,398	1,306	1,264
Operating Segments | Loews Hotels & Co
Disaggregation of Revenues
Operating revenues and other	720	479	277
Operating Segments | Loews Hotels & Co | Lodging and related services – Loews Hotels & Co
Disaggregation of Revenues
Revenues from contracts with customers	689	419	234
Operating Segments | Diamond Offshore
Disaggregation of Revenues
Operating revenues and other			305
Operating Segments | Diamond Offshore | Contract drilling - Diamond Offshore
Disaggregation of Revenues
Revenues from contracts with customers			300
Corporate
Disaggregation of Revenues
Operating revenues and other	5	281	1,023
Corporate | Rigid plastic packaging and recycled resin - Corporate
Disaggregation of Revenues
Revenues from contracts with customers		$ 280	$ 1,022