CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues
Premiums earned									$ 4,493	$ 4,214	$ 3,987
Net investment income									438	433	433
Net realized investment gains (losses)									418	(4)	313
Net impairment losses recognized in earnings									0	(2)	(6)
Equity in earnings of limited partnerships									131	149	128
Other income									32	34	35
Total revenues	1,372	1,460	1,160	1,520	1,418	796	1,245	1,365	5,512	4,824	4,890
Benefits and expenses
Insurance losses and loss expenses									3,480	3,444	2,900
Policy acquisition and underwriting expenses									1,133	1,022	969
Goodwill impairment											22
Total benefits and expenses	1,207	1,190	1,230	986	993	1,101	1,419	953	4,613	4,466	3,891
Income (loss) from operations before income taxes and noncontrolling interest	165	270	(70)	534	425	(305)	(174)	412	899	358	999
Provision for income taxes									280	90	339
Net income (loss)	119	184	(38)	354	281	(180)	(107)	274	619	268	660
Less: Net income attributable to noncontrolling interest in consolidated entity – Exchange	89	133	(81)	318	255	(227)	(159)	230	459	99	498
Net income attributable to Indemnity	30	51	43	36	26	47	52	44	160	169	162
Indemnity
Revenues
Net investment income									16	16	37
Net realized investment gains (losses)									5	3	(1)
Net impairment losses recognized in earnings									0	0	(1)
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest									241	256	269
Provision for income taxes									81	85	104
Net income attributable to Indemnity									$ 160	$ 169	$ 162
Class A | Indemnity
Net income attributable to Indemnity per share
Common stock - basic (in dollars per share)	$ 0.63	$ 1.08	$ 0.90	$ 0.76	$ 0.55	$ 0.97	$ 1.05	$ 0.88	$ 3.38	$ 3.45	$ 3.18
Common stock - diluted (in dollars per share)	$ 0.56	$ 0.96	$ 0.80	$ 0.67	$ 0.49	$ 0.87	$ 0.94	$ 0.78	$ 2.99	$ 3.08	$ 2.85
Weighted average shares outstanding attributable to Indemnity - Basic
Common stock - basic (in shares)									47,357,836	48,875,316	50,705,607
Weighted average shares outstanding attributable to Indemnity - Diluted
Common stock - diluted (in shares)									53,547,833	55,057,437	56,884,894
Class B | Indemnity
Net income attributable to Indemnity per share
Common stock - basic (in dollars per share)	$ 94	$ 162.00	$ 135.00	$ 114.00	$ 82	$ 147.00	$ 158.00	$ 126.00	$ 505.00	$ 522.00	$ 463.00
Common stock - diluted (in dollars per share)	$ 94	$ 162.00	$ 135.00	$ 114.00	$ 82	$ 147.00	$ 158.00	$ 126.00	$ 505.00	$ 522.00	$ 463.00
Weighted average shares outstanding attributable to Indemnity - Basic
Common stock - basic (in shares)									2,544	2,546	2,546
Weighted average shares outstanding attributable to Indemnity - Diluted
Common stock - diluted (in shares)									2,544	2,546	2,546