Segments (Details) $ in Millions	3 Months Ended				12 Months Ended
	Dec. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2023 USD ($) Hotel subsidiary Segment mi	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Segments [Abstract]
Number of reportable segments | Segment					4
Number of individual operating subsidiaries | subsidiary					3
Number of miles of natural gas and natural gas liquid pipelines | mi					14,310
Number of hotels | Hotel					25
Revenues:
Insurance premiums					$ 9,480	$ 8,667	$ 8,175
Net investment income					2,395	1,802	2,259
Investment gains (losses)					(53)	(199)	660
Non-insurance warranty revenue					1,624	1,574	1,430
Operating revenues and other					2,455	2,200	2,133
Total					15,901	14,044	14,657
Expenses:
Insurance claims and policyholders’ benefits					7,068	6,653	6,371
Amortization of deferred acquisition costs					1,644	1,490	1,443
Non-insurance warranty expense					1,544	1,471	1,328
Operating expenses and other					3,393	3,077	2,957
Equity method (income) loss					(120)	(139)	(26)
Interest					376	378	424
Total					13,905	12,930	12,497
Income (loss) before income tax					1,996	1,114	2,160
Income tax expense					(451)	(223)	(475)
Net income (loss)					1,545	891	1,685
Amounts attributable to noncontrolling interests					(111)	(69)	(123)
Net income (loss) attributable to Loews Corporation	$ 355	$ (22)	$ 167	$ 322	1,434	822	1,562
Assets:
Total assets	75,567				79,197	75,567
CNA Financial
Expenses:
Insurance claims and policyholders’ benefits						6,653	6,371
Income (loss) before income tax						814	1,462
Income tax expense						(133)	(278)
Net income (loss)						681	1,184
Amounts attributable to noncontrolling interests						(69)	(123)
Net income (loss) attributable to Loews Corporation						612	1,061
Operating Segments | CNA Financial
Revenues:
Insurance premiums					9,480	8,667	8,175
Net investment income					2,264	1,805	2,159
Investment gains (losses)					(99)	(199)	120
Non-insurance warranty revenue					1,624	1,574	1,430
Operating revenues and other					30	32	24
Total					13,299	11,879	11,908
Expenses:
Insurance claims and policyholders’ benefits					7,068	6,653	6,371
Amortization of deferred acquisition costs					1,644	1,490	1,443
Non-insurance warranty expense					1,544	1,471	1,328
Operating expenses and other					1,398	1,339	1,191
Equity method (income) loss
Interest					127	112	113
Total					11,781	11,065	10,446
Income (loss) before income tax					1,518	814	1,462
Income tax expense					(313)	(133)	(278)
Net income (loss)					1,205	681	1,184
Amounts attributable to noncontrolling interests					(111)	(69)	(123)
Net income (loss) attributable to Loews Corporation					1,094	612	1,061
Assets:
Total assets	60,945				64,655	60,945
Operating Segments | Boardwalk Pipelines
Revenues:
Insurance premiums
Net investment income					11	3
Investment gains (losses)
Non-insurance warranty revenue
Operating revenues and other					1,625	1,443	1,349
Total					1,636	1,446	1,349
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other					1,108	950	885
Equity method (income) loss
Interest					155	166	161
Total					1,263	1,116	1,046
Income (loss) before income tax					373	330	303
Income tax expense					(90)	(83)	(68)
Net income (loss)					283	247	235
Amounts attributable to noncontrolling interests
Net income (loss) attributable to Loews Corporation					283	247	235
Assets:
Total assets	9,640				9,785	9,640
Operating Segments | Loews Hotels & Co
Revenues:
Insurance premiums
Net investment income					6	1	1
Investment gains (losses)					46
Non-insurance warranty revenue
Operating revenues and other					800	720	479
Total					852	721	480
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other					767	697	503
Equity method (income) loss					(129)	(148)	(47)
Interest					14	11	36
Total					652	560	492
Income (loss) before income tax					200	161	(12)
Income tax expense					(53)	(44)	(2)
Net income (loss)					147	117	(14)
Amounts attributable to noncontrolling interests
Net income (loss) attributable to Loews Corporation					147	117	(14)
Assets:
Total assets	1,935				2,374	1,935
Segment Reconciling Items | Corporate
Revenues:
Insurance premiums
Net investment income					114	(7)	99
Investment gains (losses)							540
Non-insurance warranty revenue
Operating revenues and other						5	281
Total					114	(2)	920
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other					120	91	378
Equity method (income) loss					9	9	21
Interest					80	89	114
Total					209	189	513
Income (loss) before income tax					(95)	(191)	407
Income tax expense					5	37	(127)
Net income (loss)					(90)	(154)	280
Amounts attributable to noncontrolling interests
Net income (loss) attributable to Loews Corporation					(90)	(154)	$ 280
Assets:
Total assets	$ 3,047				$ 2,383	$ 3,047
United States | Loews Hotels & Co
Segments [Abstract]
Number of hotels | Hotel					24
Non-US | Loews Hotels & Co
Segments [Abstract]
Number of hotels | Hotel					1