Schedule I - Condensed Financial Information of Registrant - Parent Company Only, Statements of Income and Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Equity in income of subsidiaries									$ 41	$ 43	$ (62)
Total	$ 3,338	$ 3,287	$ 3,307	$ 3,173	$ 3,333	$ 3,169	$ 3,435	$ 3,478	13,105	13,415	14,325
Expenses:
Interest									536	520	498
Total									12,169	13,171	12,515
Income before income tax									936	244	1,810
Income tax benefit									(220)	43	(457)
Income from continuing operations									716	287	1,353
Discontinued operations, net											(391)
Net income									716	287	962
Total comprehensive income (loss) attributable to Loews Corporation									788	(378)	532
Loews Corporation [Member]
Revenues:
Equity in income of subsidiaries									655	302	1,034
Interest and other									165	74	92
Total									820	376	1,126
Expenses:
Administrative									127	108	97
Interest									72	74	74
Total									199	182	171
Income before income tax									621	194	955
Income tax benefit									33	66	7
Income from continuing operations									654	260	962
Discontinued operations, net											(371)
Net income									654	260	591
Equity in other comprehensive income (loss) of subsidiaries									134	(638)	(59)
Total comprehensive income (loss) attributable to Loews Corporation									$ 788	$ (378)	$ 532