Shareholders' Equity and Noncontrolling Interest (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 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	(38)	(107)	316	167	268
Change in other comprehensive income (loss), net of tax	12	17	84	13	(61)
Realized gain on sale of life affiliate, net of tax					8
Net purchase of treasury stock			(43)		(154)
Dividends declared:
Balance, end of period	6,597		6,597		6,293
Class A
Dividends declared:
Dividends declared			(53)		(101)
Class B
Dividends declared:
Dividends declared			0		(1)
Indemnity
Reconciliation of the beginning and ending balances of shareholders' equity and noncontrolling interest
Balance, beginning of period			781	912	912
Net income			79		169
Change in other comprehensive income (loss), net of tax			2		(52)
Realized gain on sale of life affiliate, net of tax					8
Net purchase of treasury stock			(43)		(154)
Dividends declared:
Balance, end of period	766		766		781
Indemnity | Class A
Dividends declared:
Dividends declared (in dollars per share)	$ 0.5525	$ 0.515	$ 1.105	$ 1.03	$ 2.0975
Dividends declared			(53)		(101)
Indemnity | Class B
Dividends declared:
Dividends declared (in dollars per share)	$ 82.8750	$ 77.250	$ 165.7500	$ 154.5000	$ 314.6250
Dividends declared			0		(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			237		99
Change in other comprehensive income (loss), net of tax			82		(9)
Dividends declared:
Balance, end of period	$ 5,831		$ 5,831		$ 5,512