Consolidating Financial Information (Consolidating Balance Sheet Information) (Details) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Dec. 31, 2009
Condensed Financial Statements, Captions [Line Items]
Investments	$ 49,625	$ 48,907
Cash	128	120	132	190
Receivables	10,109	10,142
Property, plant and equipment	12,935	12,636
Deferred income taxes		289
Goodwill	856	856
Investments in capital stocks of subsidiaries	0
Other assets	1,451	1,798
Deferred acquisition costs of insurance subsidiaries	783	1,079
Separate account business	418	450
Total assets	76,305	76,277
Insurance reserves	37,851	37,590
Short term debt	1,206	647
Long term debt	8,026	8,830
Payable to brokers	567	685
Deferred income taxes	802	562
Other liabilities	3,870	4,407
Separate account business	418	450
Total liabilities	52,740	53,171
Total shareholders' equity	18,974	18,450
Noncontrolling interests	4,591	4,656
Total equity	23,565	23,106	23,499	21,085
Total liabilities and equity	76,305	76,277
CNA Financial [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	44,105	42,655
Cash	84	77
Receivables	9,164	9,224
Property, plant and equipment	284	286
Deferred income taxes	234	699
Goodwill	86	86
Investments in capital stocks of subsidiaries	0
Other assets	640	724
Deferred acquisition costs of insurance subsidiaries	783	1,079
Separate account business	418	450
Total assets	55,798	55,280
Insurance reserves	37,851	37,590
Short term debt	100	400
Long term debt	2,538	2,251
Payable to brokers	283	239
Other liabilities	2,698	2,877
Separate account business	418	450
Total liabilities	43,888	43,807
Total shareholders' equity	10,603	9,838
Noncontrolling interests	1,307	1,635
Total equity	11,910	11,473
Total liabilities and equity	55,798	55,280
Diamond Offshore [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	1,129	1,055
Cash	21	22
Receivables	625	671
Property, plant and equipment	4,612	4,291
Goodwill	20	20
Investments in capital stocks of subsidiaries	0
Other assets	442	678
Total assets	6,849	6,737
Long term debt	1,488	1,487
Payable to brokers	14
Deferred income taxes	510	533
Other liabilities	553	831
Total liabilities	2,565	2,851
Total shareholders' equity	2,172	1,972
Noncontrolling interests	2,112	1,914
Total equity	4,284	3,886
Total liabilities and equity	6,849	6,737
HighMount [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	149	128
Cash	1	2
Receivables	90	109
Property, plant and equipment	1,407	1,350
Deferred income taxes	516	548
Goodwill	584	584
Investments in capital stocks of subsidiaries	0
Other assets	16	27
Total assets	2,763	2,748
Short term debt	1,100
Long term debt		1,100
Payable to brokers	86	115
Other liabilities	79	93
Total liabilities	1,265	1,308
Total shareholders' equity	1,498	1,440
Total equity	1,498	1,440
Total liabilities and equity	2,763	2,748
Boardwalk Pipeline [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	76	52
Cash	10	7
Receivables	85	71
Property, plant and equipment	6,253	6,326
Goodwill	163	163
Investments in capital stocks of subsidiaries	0
Other assets	314	339
Total assets	6,901	6,958
Long term debt	3,198	3,252
Payable to brokers		2
Deferred income taxes	469	410
Other liabilities	345	372
Total liabilities	4,012	4,036
Total shareholders' equity	1,717	1,815
Noncontrolling interests	1,172	1,107
Total equity	2,889	2,922
Total liabilities and equity	6,901	6,958
Loews Hotels [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	67	57
Cash	10	10
Receivables	33	33
Property, plant and equipment	335	347
Goodwill	3	3
Investments in capital stocks of subsidiaries	0
Other assets	23	24
Total assets	471	474
Short term debt	6	72
Long term debt	209	148
Deferred income taxes	56	54
Other liabilities	13	21
Total liabilities	284	295
Total shareholders' equity	187	179
Total equity	187	179
Total liabilities and equity	471	474
Corporate And Other [Member]
Condensed Financial Statements, Captions [Line Items]
Investments	4,099	4,960
Cash	2	2
Receivables	215	169
Property, plant and equipment	44	36
Investments in capital stocks of subsidiaries	16,272	15,314
Other assets	16	6
Total assets	20,648	20,487
Short term debt		175
Long term debt	693	692
Payable to brokers	184	329
Deferred income taxes	517	523
Other liabilities	185	248
Total liabilities	1,579	1,967
Total shareholders' equity	19,069	18,520
Total equity	19,069	18,520
Total liabilities and equity	20,648	20,487
Eliminations [Member]
Condensed Financial Statements, Captions [Line Items]
Receivables	(103)	(135)
Deferred income taxes	(750)	(958)
Investments in capital stocks of subsidiaries	(16,272)	(15,314)
Total assets	(17,125)	(16,407)
Long term debt	(100)	(100)
Deferred income taxes	(750)	(958)
Other liabilities	(3)	(35)
Total liabilities	(853)	(1,093)
Total shareholders' equity	(16,272)	(15,314)
Total equity	(16,272)	(15,314)
Total liabilities and equity	$ (17,125)	$ (16,407)