Segments (Details) $ in Millions	3 Months Ended
	Mar. 31, 2023 USD ($) subsidiary Segment	Mar. 31, 2022 USD ($)
Segments [Abstract]
Number of reportable segments | Segment	4
Number of individual operating subsidiaries | subsidiary	3
Revenues:
Insurance premiums	$ 2,248	$ 2,059
Net investment income	569	432
Investment losses	(35)	(11)
Non-insurance warranty revenue	407	382
Operating revenues and other	594	540
Total	3,783	3,402
Expenses:
Insurance claims and policyholders’ benefits	1,653	1,478
Amortization of deferred acquisition costs	379	344
Non-insurance warranty expense	384	354
Operating expenses and other	781	716
Equity method (income) loss	(28)	(25)
Interest	95	96
Total	3,264	2,963
Income (loss) before income tax	519	439
Income tax expense	(115)	(87)
Net income	404	352
Amounts attributable to noncontrolling interests	(29)	(30)
Net income attributable to Loews Corporation	375	322
CNA Financial
Expenses:
Insurance claims and policyholders’ benefits		1,478
Income tax expense		(60)
Net income		295
Amounts attributable to noncontrolling interests		(30)
Net income attributable to Loews Corporation		265
Operating Segments | CNA Financial
Revenues:
Insurance premiums	2,248	2,059
Net investment income	525	448
Investment losses	(35)	(11)
Non-insurance warranty revenue	407	382
Operating revenues and other	7	7
Total	3,152	2,885
Expenses:
Insurance claims and policyholders’ benefits	1,653	1,478
Amortization of deferred acquisition costs	379	344
Non-insurance warranty expense	384	354
Operating expenses and other	337	326
Equity method (income) loss
Interest	28	28
Total	2,781	2,530
Income (loss) before income tax	371	355
Income tax expense	(74)	(60)
Net income	297	295
Amounts attributable to noncontrolling interests	(29)	(30)
Net income attributable to Loews Corporation	268	265
Operating Segments | Boardwalk Pipelines
Revenues:
Insurance premiums
Net investment income	1
Investment losses
Non-insurance warranty revenue
Operating revenues and other	396	381
Total	397	381
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	242	217
Equity method (income) loss
Interest	39	42
Total	281	259
Income (loss) before income tax	116	122
Income tax expense	(30)	(31)
Net income	86	91
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	86	91
Operating Segments | Loews Hotels & Co
Revenues:
Insurance premiums
Net investment income	1
Investment losses
Non-insurance warranty revenue
Operating revenues and other	191	152
Total	192	152
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	183	152
Equity method (income) loss	(31)	(26)
Interest	6	4
Total	158	130
Income (loss) before income tax	34	22
Income tax expense	(10)	(7)
Net income	24	15
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	24	15
Corporate
Revenues:
Insurance premiums
Net investment income	42	(16)
Investment losses
Non-insurance warranty revenue
Operating revenues and other
Total	42	(16)
Expenses:
Insurance claims and policyholders’ benefits
Amortization of deferred acquisition costs
Non-insurance warranty expense
Operating expenses and other	19	21
Equity method (income) loss	3	1
Interest	22	22
Total	44	44
Income (loss) before income tax	(2)	(60)
Income tax expense	(1)	11
Net income	(3)	(49)
Amounts attributable to noncontrolling interests
Net income attributable to Loews Corporation	$ (3)	$ (49)