CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Revenues
Premiums earned	$ 1,241	$ 1,137	$ 3,631	$ 3,333
Net investment income	109	105	316	326
Net realized investment gains (losses)	191	169	501	358
Net impairment losses recognized in earnings	(9)	0	(10)	0
Equity in earnings of limited partnerships	37	41	112	99
Other income	8	8	24	24
Total revenues	1,577	1,460	4,574	4,140
Benefits and expenses
Insurance losses and loss expenses	868	912	2,571	2,571
Policy acquisition and underwriting expenses	311	278	906	835
Total benefits and expenses	1,179	1,190	3,477	3,406
Income (loss) from operations before income taxes and noncontrolling interest	398	270	1,097	734
Provision for income taxes	131	86	363	234
Net income (loss)	267	184	734	500	619
Less: Net income attributable to noncontrolling interest in consolidated entity – Exchange	221	133	607	370
Net income attributable to Indemnity	46	51	127	130
Indemnity
Revenues
Net investment income	4	4	11	12
Net realized investment gains (losses)	1	2	1	4
Net impairment losses recognized in earnings	0	0	0	0
Benefits and expenses
Income (loss) from operations before income taxes and noncontrolling interest	70	78	193	197
Provision for income taxes	24	27	66	67
Net income (loss)			127		160
Net income attributable to Indemnity	$ 46	$ 51	$ 127	$ 130
Class A | Indemnity
Net income attributable to Indemnity per share
Common stock - basic (in dollars per share)	$ 0.98	$ 1.08	$ 2.71	$ 2.73
Common stock - diluted (in dollars per share)	$ 0.87	$ 0.96	$ 2.41	$ 2.43
Weighted average shares outstanding attributable to Indemnity - Basic
Common stock - basic (in shares)	46,656,911	47,188,741	46,707,971	47,476,693
Weighted average shares outstanding attributable to Indemnity - Diluted
Common stock - diluted (in shares)	52,851,250	53,374,846	52,902,310	53,662,798
Dividends declared per share
Common stock (in dollars per share)	$ 0.5925	$ 0.5525	$ 1.7775	$ 1.6575	$ 4.25
Class B | Indemnity
Net income attributable to Indemnity per share
Common stock - basic (in dollars per share)	$ 147.00	$ 162.00	$ 406.00	$ 411.00
Common stock - diluted (in dollars per share)	$ 147.00	$ 162.00	$ 406.00	$ 411.00
Weighted average shares outstanding attributable to Indemnity - Basic
Common stock - basic (in shares)	2,542	2,544	2,542	2,544
Weighted average shares outstanding attributable to Indemnity - Diluted
Common stock - diluted (in shares)	2,542	2,544	2,542	2,544
Dividends declared per share
Common stock (in dollars per share)	$ 88.8750	$ 82.8750	$ 266.6250	$ 248.6250	$ 637.5000