Segments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2026 USD ($) segment subsidiary	Mar. 31, 2025 USD ($)	Dec. 31, 2025 USD ($)
Segments:
Number of reportable segments | segment	4
Number of individual operating subsidiaries | subsidiary	3
Revenues:
Insurance premiums	$ 2,699	$ 2,626
Net investment income (loss)	613	608
Investment losses	(18)	(9)
Non-insurance warranty revenue	374	397
Operating revenues and other	887	872
Total	4,555	4,494
Expenses:
Insurance claims and policyholders’ benefits	2,175	2,027
Amortization of deferred acquisition costs	476	471
Non-insurance warranty expense	356	385
Operating expenses and other	1,009	991
Equity method (income) loss	(37)	1
Interest	113	105
Total	4,092	3,980
Income before income tax	463	514
Income tax (expense) benefit	(109)	(122)
Net income	354	392
Amounts attributable to noncontrolling interests	(17)	(22)
Net income attributable to Loews Corporation	337	370
Assets:
Total assets	85,652	83,142	$ 86,348
Total pretax unfavorable development	100	83
Operating Expenses and Other:
Insurance related administrative expenses	332	321
Operating expenses	329	345
Depreciation and amortization	138	131
Other	210	194
Operating expenses and other	1,009	991
Total property & casualty operations
Assets:
Total pretax unfavorable development	100	61
Operating Segments | CNA Financial
Revenues:
Insurance premiums	2,701	2,626
Net investment income (loss)	610	604
Investment losses	(18)	(9)
Non-insurance warranty revenue	374	397
Operating revenues and other	10	9
Total	3,677	3,627
Expenses:
Insurance claims and policyholders’ benefits	2,175	2,027
Amortization of deferred acquisition costs	476	471
Non-insurance warranty expense	356	385
Operating expenses and other	370	363
Equity method (income) loss
Interest	33	32
Total	3,410	3,278
Income before income tax	267	349
Income tax (expense) benefit	(56)	(75)
Net income	211	274
Amounts attributable to noncontrolling interests	(17)	(22)
Net income attributable to Loews Corporation	194	252
Assets:
Total assets	68,520	67,288
Operating Expenses and Other:
Insurance related administrative expenses	332	321
Operating expenses
Depreciation and amortization
Other	38	42
Operating expenses and other	370	363
Operating Segments | CNA Financial | Total property & casualty operations
Assets:
Loss from catastrophes	88	97
Total pretax unfavorable development	100	83
Operating Segments | Boardwalk Pipelines
Revenues:
Insurance premiums
Net investment income (loss)	5	1
Investment losses
Non-insurance warranty revenue
Operating revenues and other	626	621
Total	631	622
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	377	381
Equity method (income) loss
Interest	43	39
Total	420	420
Income before income tax	211	202
Income tax (expense) benefit	(52)	(50)
Net income	159	152
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	159	152
Assets:
Total assets	10,189	9,919
Operating Expenses and Other:
Insurance related administrative expenses
Operating expenses	176	192
Depreciation and amortization	111	106
Other	90	83
Operating expenses and other	377	381
Operating Segments | Loews Hotels & Co
Revenues:
Insurance premiums
Net investment income (loss)	3	3
Investment losses
Non-insurance warranty revenue
Operating revenues and other	251	242
Total	254	245
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	246	231
Equity method (income) loss	(44)	(6)
Interest	15	16
Total	217	241
Income before income tax	37	4
Income tax (expense) benefit	(11)	(4)
Net income	26	0
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	26	0
Assets:
Total assets	2,532	2,500
Operating Expenses and Other:
Insurance related administrative expenses
Operating expenses	153	153
Depreciation and amortization	26	24
Other	67	54
Operating expenses and other	246	231
Corporate, Reconciling Items and Eliminations | Corporate
Revenues:
Insurance premiums	(2)
Net investment income (loss)	(5)
Investment losses
Non-insurance warranty revenue
Operating revenues and other
Total	(7)	0
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	16	16
Equity method (income) loss	7	7
Interest	22	18
Total	45	41
Income before income tax	(52)	(41)
Income tax (expense) benefit	10	7
Net income	(42)	(34)
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	(42)	(34)
Assets:
Total assets	4,411	3,435
Operating Expenses and Other:
Insurance related administrative expenses
Operating expenses
Depreciation and amortization	1	1
Other	15	15
Operating expenses and other	$ 16	$ 16