Schedule I - Condensed Financial Information of Registrant, Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities [Abstract]
Net income	$ (1,291)	$ 871	$ 706
Adjustments to reconcile net income to net cash provided (used) by operating activities [Abstract]
Equity method investees	102	20	572
Provision for deferred income taxes	(235)	70	86
Changes in operating assets and liabilities, net [Abstract]
Receivables	(425)	114	(131)
Trading securities	(571)	(494)	1,702
Net cash flow provided by operating activities	1,745	1,741	4,222
Investing Activities [Abstract]
Change in investments, primarily short term	427	(57)	(339)
Other	(127)	(206)	(60)
Net cash flow used by investing activities	(1,414)	(671)	(1,444)
Financing Activities [Abstract]
Dividends paid	(70)	(76)	(80)
Purchases of treasury shares	(923)	(1,051)	(1,026)
Issuance of debt	2,659	2,076	865
Other	(2)	(16)	74
Net cash flow (used) provided by financing activities	(198)	(1,144)	(2,835)
Net change in cash	142	(69)	(67)
Cash, beginning of year	336	405	472
Cash, end of year	478	336	405
Loews Corporation [Member]
Operating Activities [Abstract]
Net income	(931)	932	636
Adjustments to reconcile net income to net cash provided (used) by operating activities [Abstract]
Equity method investees	834	36	401
Loss on deconsolidation	1,211
Provision for deferred income taxes	(196)	106	113
Changes in operating assets and liabilities, net [Abstract]
Receivables		1	3
Accounts payable and accrued liabilities	(38)	(29)	92
Trading securities	(566)	(478)	1,702
Other, net	44	36	19
Net cash flow provided by operating activities	358	604	2,966
Investing Activities [Abstract]
Investments in and advances to subsidiaries	(169)	183	(135)
Change in investments, primarily short term	326	326	(187)
Purchase of Boardwalk Pipelines common units			(1,504)
Other			(2)
Net cash flow used by investing activities	157	509	(1,828)
Financing Activities [Abstract]
Dividends paid	(70)	(76)	(80)
Purchases of treasury shares	(923)	(1,051)	(1,026)
Issuance of debt	495
Other	(5)	(5)	(3)
Net cash flow (used) provided by financing activities	(503)	(1,132)	(1,109)
Net change in cash	12	(19)	29
Cash, beginning of year	10	29
Cash, end of year	22	10	29
Cash dividends paid to Company by affiliates	$ 947	$ 927	$ 878