Segments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2024 USD ($) Segment subsidiary	Mar. 31, 2023 USD ($)
Segments [Abstract]
Number of reportable segments | Segment	4
Number of individual operating subsidiaries | subsidiary	3
Revenues:
Insurance premiums	$ 2,441	$ 2,248
Net investment income	669	569
Investment losses	(22)	(35)
Non-insurance warranty revenue	407	407
Operating revenues and other	736	594
Total	4,231	3,783
Expenses:
Insurance claims and policyholders’ benefits	1,807	1,653
Amortization of deferred acquisition costs	444	379
Non-insurance warranty expense	394	384
Operating expenses and other	880	781
Equity method (income) loss	(26)	(28)
Interest	103	95
Total	3,602	3,264
Income before income tax	629	519
Income tax expense	(144)	(115)
Net income	485	404
Amounts attributable to noncontrolling interests	(28)	(29)
Net income attributable to Loews Corporation	457	375
Operating Segments | CNA Financial
Revenues:
Insurance premiums	2,441	2,248
Net investment income	609	525
Investment losses	(22)	(35)
Non-insurance warranty revenue	407	407
Operating revenues and other	9	7
Total	3,444	3,152
Expenses:
Insurance claims and policyholders’ benefits	1,807	1,653
Amortization of deferred acquisition costs	444	379
Non-insurance warranty expense	394	384
Operating expenses and other	337	337
Equity method (income) loss
Interest	35	28
Total	3,017	2,781
Income before income tax	427	371
Income tax expense	(89)	(74)
Net income	338	297
Amounts attributable to noncontrolling interests	(28)	(29)
Net income attributable to Loews Corporation	310	268
Operating Segments | Boardwalk Pipelines
Revenues:
Insurance premiums
Net investment income	4	1
Investment losses
Non-insurance warranty revenue
Operating revenues and other	513	396
Total	517	397
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	312	242
Equity method (income) loss
Interest	43	39
Total	355	281
Income before income tax	162	116
Income tax expense	(41)	(30)
Net income	121	86
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	121	86
Operating Segments | Loews Hotels & Co
Revenues:
Insurance premiums
Net investment income	2	1
Investment losses
Non-insurance warranty revenue
Operating revenues and other	214	191
Total	216	192
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	209	183
Equity method (income) loss	(27)	(31)
Interest	6	6
Total	188	158
Income before income tax	28	34
Income tax expense	(12)	(10)
Net income	16	24
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	16	24
Segment Reconciling Items | Corporate
Revenues:
Insurance premiums
Net investment income	54	42
Investment losses
Non-insurance warranty revenue
Operating revenues and other
Total	54	42
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	22	19
Equity method (income) loss	1	3
Interest	19	22
Total	42	44
Income before income tax	12	(2)
Income tax expense	(2)	(1)
Net income	10	(3)
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	$ 10	$ (3)