Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shareholders Equity [Line Items]
Common stock dividend declared	$ 0.25	$ 0.25	$ 0.25
Common stock dividend paid	$ 0.25	$ 0.25	$ 0.25
Increase (decrease) in Additional paid-in capital	$ (2)
Common stock, shares issued	339,897,547	372,934,540
Increase in accumulated other comprehensive income	$ 1		$ 2
Treasury stock repurchased, shares	33,300,000	14,600,000	4,900,000
Purchase of Loews treasury stock	$ 1,265	$ 622	$ 218
Diamond Offshore [Member]
Shareholders Equity [Line Items]
Purchase of common stock	1,100,000
Common stock, aggregate cost	$ 29
Increase (decrease) in Additional paid-in capital	$ 5
Diamond Offshore [Member] | Minimum [Member]
Shareholders Equity [Line Items]
Subsidiary ownership percentage	52.00%
Diamond Offshore [Member] | Maximum [Member]
Shareholders Equity [Line Items]
Subsidiary ownership percentage	53.00%
Boardwalk Pipeline [Member]
Shareholders Equity [Line Items]
Common stock, shares issued	7,100,000
Proceeds from subsidiary public offering	$ 115
Contribution from the company	$ 2
General partner interest	2.00%
Boardwalk Pipeline [Member] | Minimum [Member]
Shareholders Equity [Line Items]
Subsidiary ownership percentage	51.00%
Boardwalk Pipeline [Member] | Maximum [Member]
Shareholders Equity [Line Items]
Subsidiary ownership percentage	53.00%