Goodwill - Schedule of Changes in Goodwill (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill, beginning balance	$ 374	$ 357
Impairments	(20)
Additions		22
Dispositions		(3)
Other adjustments	(3)	(2)
Goodwill, ending balance	351	374
CNA Financial [Member]
Goodwill [Line Items]
Goodwill, beginning balance	117	119
Other adjustments	(3)	(2)
Goodwill, ending balance	114	117
Diamond Offshore [Member]
Goodwill [Line Items]
Goodwill, beginning balance	20	20
Impairments	(20)
Goodwill, ending balance		20
Boardwalk Pipeline [Member]
Goodwill [Line Items]
Goodwill, beginning balance	237	215
Additions		22
Goodwill, ending balance	$ 237	237
Loews Hotels [Member]
Goodwill [Line Items]
Goodwill, beginning balance		3
Dispositions		$ (3)