Consolidating Financial Information (Consolidating Balance Sheet Information) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Condensed Financial Statements, Captions [Line Items]
Investments	$ 50,958	$ 49,028
Cash	99	129	123	120
Receivables	9,409	9,259
Property, plant and equipment	13,522	13,618
Goodwill	908	908
Other assets	1,366	1,357
Deferred acquisition costs of insurance subsidiaries	576	552
Separate account business	402	417
Total assets	77,240	75,268
Insurance reserves	37,714	37,554
Payable to brokers	920	162
Short term debt	88	88
Long term debt	8,954	8,913
Deferred income taxes	937	622
Other liabilities	4,104	4,309
Separate account business	402	417
Total liabilities	53,119	52,065
Total shareholders' equity	19,428	18,772
Noncontrolling interests	4,693	4,431
Total equity	24,121	23,203	23,364	23,028
Total liabilities and equity	77,240	75,268
CNA Financial [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	45,465	44,372
Cash	59	75
Receivables	8,295	8,302
Property, plant and equipment	272	272
Deferred income taxes	229	444
Goodwill	86	86
Other assets	579	544
Deferred acquisition costs of insurance subsidiaries	576	552
Separate account business	402	417
Total assets	55,963	55,064
Insurance reserves	37,714	37,554
Payable to brokers	404	72
Short term debt	83	83
Long term debt	2,526	2,525
Other liabilities	2,896	2,971
Separate account business	402	417
Total liabilities	44,025	43,622
Total shareholders' equity	10,759	10,315
Noncontrolling interests	1,179	1,127
Total equity	11,938	11,442
Total liabilities and equity	55,963	55,064
Diamond Offshore [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	1,368	1,206
Cash	32	30
Receivables	577	594
Property, plant and equipment	4,617	4,674
Goodwill	20	20
Other assets	424	453
Total assets	7,038	6,977
Payable to brokers	1	8
Long term debt	1,489	1,488
Deferred income taxes	532	530
Other liabilities	589	594
Total liabilities	2,611	2,620
Total shareholders' equity	2,244	2,209
Noncontrolling interests	2,183	2,148
Total equity	4,427	4,357
Total liabilities and equity	7,038	6,977
Boardwalk Pipeline [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	2	10
Cash	2	13
Receivables	100	114
Property, plant and equipment	6,673	6,713
Goodwill	215	215
Other assets	298	307
Total assets	7,290	7,372
Payable to brokers	1	1
Long term debt	3,439	3,398
Deferred income taxes	534	493
Other liabilities	307	373
Total liabilities	4,281	4,265
Total shareholders' equity	1,678	1,951
Noncontrolling interests	1,331	1,156
Total equity	3,009	3,107
Total liabilities and equity	7,290	7,372
HighMount [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	49	85
Receivables	108	109
Property, plant and equipment	1,574	1,576
Deferred income taxes	505	499
Goodwill	584	584
Other assets	22	19
Total assets	2,842	2,872
Payable to brokers	24	36
Long term debt	700	700
Other liabilities	97	104
Total liabilities	821	840
Total shareholders' equity	2,021	2,032
Total equity	2,021	2,032
Total liabilities and equity	2,842	2,872
Loews Hotels [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	72	71
Cash	6	10
Receivables	34	33
Property, plant and equipment	338	338
Goodwill	3	3
Other assets	24	23
Total assets	477	478
Short term debt	5	5
Long term debt	208	208
Deferred income taxes	50	51
Other liabilities	14	20
Total liabilities	277	284
Total shareholders' equity	200	194
Total equity	200	194
Total liabilities and equity	477	478
Corporate And Other [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	4,002	3,284
Cash		1
Receivables	419	226
Property, plant and equipment	48	45
Investments in capital stocks of subsidiaries	17,014	16,807
Other assets	19	11
Total assets	21,502	20,374
Payable to brokers	490	45
Long term debt	692	694
Deferred income taxes	555	491
Other liabilities	225	266
Total liabilities	1,962	1,496
Total shareholders' equity	19,540	18,878
Total equity	19,540	18,878
Total liabilities and equity	21,502	20,374
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Receivables	(124)	(119)
Deferred income taxes	(734)	(943)
Investments in capital stocks of subsidiaries	(17,014)	(16,807)
Total assets	(17,872)	(17,869)
Long term debt	(100)	(100)
Deferred income taxes	(734)	(943)
Other liabilities	(24)	(19)
Total liabilities	(858)	(1,062)
Total shareholders' equity	(17,014)	(16,807)
Total equity	(17,014)	(16,807)
Total liabilities and equity	$ (17,872)	$ (17,869)