Segments (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) subsidiary Segment	Sep. 30, 2021 USD ($)
Segments [Abstract]
Number of reportable segments | Segment			4
Number of individual operating subsidiaries | subsidiary			3
Revenues:
Insurance premiums	$ 2,221	$ 2,059	$ 6,435	$ 6,056
Net investment income (loss)	404	483	1,202	1,649
Investment losses	(96)	22	(166)	657
Non-insurance warranty revenue	399	357	1,173	1,054
Operating revenues and other	533	450	1,607	1,580
Total	3,461	3,371	10,251	10,996
Expenses:
Insurance claims and policyholders’ benefits	1,665	1,632	4,703	4,684
Amortization of deferred acquisition costs	383	368	1,101	1,084
Non-insurance warranty expense	371	330	1,092	973
Operating expenses and other	760	638	2,166	2,208
Interest	92	99	284	324
Total	3,271	3,067	9,346	9,273
Income tax expense	(47)	(58)	(190)	(391)
Net income	143	246	715	1,332
Amounts attributable to noncontrolling interests	(13)	(26)	(67)	(97)
Net income (loss) attributable to Loews Corporation	130	220	648	1,235
Operating Segments
Revenues:
Insurance premiums	2,221	2,059	6,435	6,056
Net investment income (loss)	404	483	1,202	1,649
Investment losses	(96)	22	(166)	657
Non-insurance warranty revenue	399	357	1,173	1,054
Operating revenues and other	533	450	1,607	1,580
Total	3,461	3,371	10,251	10,996
Expenses:
Insurance claims and policyholders’ benefits	1,665	1,632	4,703	4,684
Amortization of deferred acquisition costs	383	368	1,101	1,084
Non-insurance warranty expense	371	330	1,092	973
Operating expenses and other	760	638	2,166	2,208
Interest	92	99	284	324
Total	3,271	3,067	9,346	9,273
Income (loss) before income tax	190	304	905	1,723
Income tax expense	(47)	(58)	(190)	(391)
Net income	143	246	715	1,332
Amounts attributable to noncontrolling interests	(13)	(26)	(67)	(97)
Net income (loss) attributable to Loews Corporation	130	220	648	1,235
Operating Segments | CNA Financial
Revenues:
Insurance premiums	2,221	2,059	6,435	6,056
Net investment income (loss)	422	513	1,302	1,608
Investment losses	(96)	22	(166)	117
Non-insurance warranty revenue	399	357	1,173	1,054
Operating revenues and other	11	8	24	19
Total	2,957	2,959	8,768	8,854
Expenses:
Insurance claims and policyholders’ benefits	1,665	1,632	4,703	4,684
Amortization of deferred acquisition costs	383	368	1,101	1,084
Non-insurance warranty expense	371	330	1,092	973
Operating expenses and other	346	287	1,001	874
Interest	28	28	84	85
Total	2,793	2,645	7,981	7,700
Income (loss) before income tax	164	314	787	1,154
Income tax expense	(36)	(59)	(141)	(219)
Net income	128	255	646	935
Amounts attributable to noncontrolling interests	(13)	(26)	(67)	(97)
Net income (loss) attributable to Loews Corporation	115	229	579	838
Operating Segments | Boardwalk Pipelines
Revenues:
Insurance premiums
Net investment income (loss)	1		1
Investment losses
Non-insurance warranty revenue
Operating revenues and other	338	307	1,044	991
Total	339	307	1,045	991
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	250	215	698	641
Interest	42	40	126	121
Total	292	255	824	762
Income (loss) before income tax	47	52	221	229
Income tax expense	(13)	(14)	(57)	(59)
Net income	34	38	164	170
Amounts attributable to noncontrolling interests
Net income (loss) attributable to Loews Corporation	34	38	164	170
Operating Segments | Loews Hotels & Co
Revenues:
Insurance premiums
Net investment income (loss)			(1)	1
Investment losses
Non-insurance warranty revenue
Operating revenues and other	180	134	533	288
Total	180	134	532	289
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	147	109	405	328
Interest	(1)	8	7	25
Total	146	117	412	353
Income (loss) before income tax	34	17	120	(64)
Income tax expense	(9)	(4)	(36)	13
Net income	25	13	84	(51)
Amounts attributable to noncontrolling interests
Net income (loss) attributable to Loews Corporation	25	13	84	(51)
Operating Segments | Corporate
Revenues:
Insurance premiums
Net investment income (loss)	(19)	(30)	(100)	40
Investment losses				540
Non-insurance warranty revenue
Operating revenues and other	4	1	6	282
Total	(15)	(29)	(94)	862
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	17	27	62	365
Interest	23	23	67	93
Total	40	50	129	458
Income (loss) before income tax	(55)	(79)	(223)	404
Income tax expense	11	19	44	(126)
Net income	(44)	(60)	(179)	278
Amounts attributable to noncontrolling interests
Net income (loss) attributable to Loews Corporation	$ (44)	$ (60)	$ (179)	$ 278