Debt - Schedule of Debt by Subsidiary (Detail) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal	$ 11,488	$ 11,653
Unamortized Discount and Issuance Costs	112	120
Net	11,376	11,533
Short Term Debt	17	280
Long term debt	11,359	11,253
Net	11,376	11,533
Loews Corporation [Member]
Debt Instrument [Line Items]
Principal	1,800
Unamortized Discount and Issuance Costs	22
Net	1,778
Long term debt	1,778
Net	1,778
CNA Financial [Member]
Debt Instrument [Line Items]
Principal	2,694
Unamortized Discount and Issuance Costs	13
Net	2,681
Long term debt	2,681
Net	2,681
Diamond Offshore [Member]
Debt Instrument [Line Items]
Principal	2,000
Unamortized Discount and Issuance Costs	26
Net	1,974
Long term debt	1,974
Net	1,974
Boardwalk Pipeline [Member]
Debt Instrument [Line Items]
Principal	3,728
Unamortized Discount and Issuance Costs	26
Net	3,702
Short Term Debt	1
Long term debt	3,701
Net	3,702
Loews Hotels And Co [Member]
Debt Instrument [Line Items]
Principal	653	$ 648
Unamortized Discount and Issuance Costs	11
Net	642
Long term debt	642
Net	642
Consolidated Container [Member]
Debt Instrument [Line Items]
Principal	613
Unamortized Discount and Issuance Costs	14
Net	599
Short Term Debt	16
Long term debt	583
Net	$ 599

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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