Consolidating Financial Information (Consolidating Statement Of Income Information) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2009	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Insurance premiums		$ 6,603		$ 6,515		$ 6,721
Net investment income		2,063		2,508		2,499
Investment gains (losses)		(52)	[1]	56	[1]	(853)	[1]
Contract drilling revenues		3,254		3,230		3,537
Other		2,259		2,306		2,213
Total		14,127		14,615		14,117
Insurance claims and policyholders' benefits		5,489		4,985		5,290
Amortization of deferred acquisition costs		1,410		1,387		1,417
Contract drilling expenses		1,549		1,391		1,224
Other operating expenses		2,925		3,433		2,972
Impairment of natural gas and oil properties	1,000					1,036
Interest		522		517		448
Total		11,895		11,713		12,387
Income before income tax		2,232		2,902		1,730
Income tax (expense) benefit		(536)		(895)		(345)
Income from continuing operations		1,696		2,007		1,385
Discontinued operations, net				(20)		(2)
Net income		1,696		1,987		1,383
Amounts attributable to noncontrolling interests		(632)		(699)		(819)
Net income attributable to Loews Corporation		1,064		1,288		564
CNA Financial [Member]
Condensed Financial Statements, Captions [Line Items]
Insurance premiums		6,603		6,515		6,721
Net investment income		2,054		2,316		2,320
Investment gains (losses)		(19)		86		(857)
Other		323		291		288
Total		8,961		9,208		8,472
Insurance claims and policyholders' benefits		5,489		4,985		5,290
Amortization of deferred acquisition costs		1,410		1,387		1,417
Other operating expenses		992		1,558		1,086
Interest		185		157		128
Total		8,076		8,087		7,921
Income before income tax		885		1,121		551
Income tax (expense) benefit		(248)		(336)		(61)
Income from continuing operations				785		490
Discontinued operations, net				(20)		(2)
Net income		637		765		488
Amounts attributable to noncontrolling interests		(78)		(129)		(91)
Net income attributable to Loews Corporation		559		636		397
Diamond Offshore [Member]
Condensed Financial Statements, Captions [Line Items]
Net investment income		7		3		4
Investment gains (losses)		1				1
Contract drilling revenues		3,254		3,230		3,537
Other		73		128		112
Total		3,335		3,361		3,654
Contract drilling expenses		1,549		1,391		1,224
Other operating expenses		535		546		515
Interest		73		91		50
Total		2,157		2,028		1,789
Income before income tax		1,178		1,333		1,865
Income tax (expense) benefit		(250)		(413)		(540)
Income from continuing operations				920		1,325
Net income		928		920		1,325
Amounts attributable to noncontrolling interests		(477)		(474)		(682)
Net income attributable to Loews Corporation		451		446		643
HighMount [Member]
Condensed Financial Statements, Captions [Line Items]
Investment gains (losses)		(34)		(30)
Other		390		455		620
Total		356		425		620
Other operating expenses		245		258		343
Impairment of natural gas and oil properties						1,036
Interest		46		61		80
Total		291		319		1,459
Income before income tax		65		106		(839)
Income tax (expense) benefit		(24)		(48)		302
Income from continuing operations				58		(537)
Net income		41		58		(537)
Net income attributable to Loews Corporation		41		58		(537)
Boardwalk Pipeline [Member]
Condensed Financial Statements, Captions [Line Items]
Net investment income				1
Other		1,144		1,128		910
Total		1,144		1,129		910
Other operating expenses		760		695		621
Interest		173		151		132
Total		933		846		753
Income before income tax		211		283		157
Income tax (expense) benefit		(57)		(73)		(44)
Income from continuing operations				210		113
Net income		154		210		113
Amounts attributable to noncontrolling interests		(77)		(96)		(46)
Net income attributable to Loews Corporation		77		114		67
Loews Hotels [Member]
Condensed Financial Statements, Captions [Line Items]
Net investment income		1		1
Other		336		307		284
Total		337		308		284
Other operating expenses		311		296		327
Interest		9		10		9
Total		320		306		336
Income before income tax		17		2		(52)
Income tax (expense) benefit		(4)		(1)		18
Income from continuing operations				1		(34)
Net income		13		1		(34)
Net income attributable to Loews Corporation		13		1		(34)
Corporate And Other [Member]
Condensed Financial Statements, Captions [Line Items]
Net investment income		1		187		175
Intercompany interest and dividends		624		720		954
Investment gains (losses)						3
Other		(2)		(3)		(1)
Total		623		904		1,131
Other operating expenses		87		80		80
Interest		44		55		56
Total		131		135		136
Income before income tax		492		769		995
Income tax (expense) benefit		47		(24)		(20)
Income from continuing operations				745		975
Net income		539		745		975
Net income attributable to Loews Corporation		539		745		975
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Intercompany interest and dividends		(624)		(720)		(954)
Other		(5)
Total		(629)		(720)		(954)
Other operating expenses		(5)
Interest		(8)		(8)		(7)
Total		(13)		(8)		(7)
Income before income tax		(616)		(712)		(947)
Income from continuing operations				(712)		(947)
Net income		(616)		(712)		(947)
Net income attributable to Loews Corporation		$ (616)		$ (712)		$ (947)

[1] Includes gross realized gains of $299, $525 and $973 and gross realized losses of $322, $435 and $1,897 on available-for-sale securities for the years ended December 31, 2011, 2010 and 2009.