Property, Plant and Equipment - Depreciation Expense and Capital Expenditures (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Abstract]
Depreciation	$ 534	$ 509	$ 503
Capital Expend.	693	675	489
Interest costs capitalized	32	17	12
Operating Segments \| CNA Financial
Property, Plant and Equipment [Abstract]
Depreciation	54	49	51
Capital Expend.	97	50	26
Operating Segments \| Boardwalk Pipelines
Property, Plant and Equipment [Abstract]
Depreciation	410	394	368
Capital Expend.	383	352	340
Operating Segments \| Loews Hotels & Co
Property, Plant and Equipment [Abstract]
Depreciation	69	64	63
Capital Expend.	201	264	100
Segment Reconciling Items \| Corporate
Property, Plant and Equipment [Abstract]
Depreciation	1	2	21
Capital Expend.	$ 12	$ 9	$ 23

The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

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- Definition

Amount of interest capitalized during the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483013/835-20-50-1

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

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- Definition

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

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