Revenue from Contracts with Customers - Disaggregation of Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenues
Revenues from contracts with customers	$ 2,360	$ 2,087	$ 2,005
Other revenues	95	113	128
Operating revenues and other	2,455	2,200	2,133
Deferred Revenue
Revenue recognized	1,400	1,400
Contract Costs
Capitalized contract cost	3,661	3,671
Amortization of contract costs	1,200	1,200
Adjustments to deferred costs	0	0
Receivables
Receivables from Contracts with Customers
Receivables from contracts with customers	228	168
Other liabilities
Deferred Revenue
Deferred revenue	4,800	4,800
Deferred Non-insurance Warranty Acquisition Expenses
Contract Costs
Capitalized contract cost	3,700	3,700
Operating Segments | CNA Financial
Disaggregation of Revenues
Operating revenues and other	30	32	24
Operating Segments | CNA Financial | Non-insurance warranty – CNA Financial
Disaggregation of Revenues
Revenues from contracts with customers	1,624	1,574	1,430
Operating Segments | Boardwalk Pipelines
Disaggregation of Revenues
Operating revenues and other	1,625	1,443	1,349
Operating Segments | Boardwalk Pipelines | Transportation and storage of natural gas and NGLs and ethane supply and transportation services – Boardwalk Pipelines
Disaggregation of Revenues
Revenues from contracts with customers	1,582	1,398	1,306
Operating Segments | Loews Hotels & Co
Disaggregation of Revenues
Operating revenues and other	800	720	479
Operating Segments | Loews Hotels & Co | Lodging and related services – Loews Hotels & Co
Disaggregation of Revenues
Revenues from contracts with customers	778	689	419
Segment Reconciling Items | Corporate
Disaggregation of Revenues
Operating revenues and other		5	281
Segment Reconciling Items | Corporate | Rigid plastic packaging and recycled resin - Corporate
Disaggregation of Revenues
Revenues from contracts with customers			$ 280