Indemnity Shareholders' Equity and Noncontrolling Interest (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Reconciliation of the beginning and ending balances of shareholders' equity and noncontrolling interest
Balance, beginning of period			$ 6,293	$ 6,334	$ 6,334
Net income	184	(180)	500	(13)	268
Change in other comprehensive income (loss), net of tax	99	(37)	183	(24)	(61)
Realized gain on sale of life affiliate, net of tax					8
Net purchase of treasury stock			(54)		(154)
Dividends declared:
Balance, end of period	6,843		6,843		6,293
Class A
Dividends declared:
Dividends declared			(78)		(101)
Class B
Dividends declared:
Dividends declared			(1)		(1)
Indemnity
Reconciliation of the beginning and ending balances of shareholders' equity and noncontrolling interest
Balance, beginning of period			781	912	912
Net income			130		169
Change in other comprehensive income (loss), net of tax			4		(52)
Realized gain on sale of life affiliate, net of tax					8
Net purchase of treasury stock			(54)		(154)
Dividends declared:
Balance, end of period	782		782		781
Indemnity | Class A
Dividends declared:
Dividends declared (in dollars per share)	$ 0.5525	$ 0.515	$ 1.6575	$ 1.545	$ 2.0975
Dividends declared			(78)		(101)
Indemnity | Class B
Dividends declared:
Dividends declared (in dollars per share)	$ 82.8750	$ 77.250	$ 249	$ 232	$ 315
Dividends declared			(1)		(1)
Exchange
Reconciliation of the beginning and ending balances of shareholders' equity and noncontrolling interest
Balance, beginning of period			5,512	5,422	5,422
Net income			370		99
Change in other comprehensive income (loss), net of tax			179		(9)
Dividends declared:
Balance, end of period	$ 6,061		$ 6,061		$ 5,512