CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Cash and cash equivalents	$ 185	$ 430
Other assets	441	489
Indemnity
Fixed maturities, amortized cost	535	257
Equity securities, cost	24	20
Trading securities, cost	23	21
Limited partnerships, cost	185	202
Cash and cash equivalents	11	310
Other assets	119	132
Treasury stock (in shares)	20,427,758	18,235,094
Exchange
Fixed maturities, amortized cost	6,829	6,863
Equity securities, cost	531	503
Trading securities, cost	2,021	1,773
Limited partnerships, cost	1,003	1,083
Cash and cash equivalents	174	120
Other assets	$ 322	$ 357
Class A | Indemnity
Common stock, stated value per share	$ 0.0292	$ 0.0292
Common stock, authorized (in shares)	74,996,930	74,996,930
Common stock, issued (in shares)	68,289,600	68,289,600
Common stock, outstanding (in shares)	47,861,842	50,054,506
Class B
Ratio for converting shares of Class B common stock into shares of Class A common stock, numerator (in Class A shares)	2,400
Ratio for converting shares of Class B common stock into shares of Class A common stock, denominator (in Class B shares)	1
Class B | Indemnity
Ratio for converting shares of Class B common stock into shares of Class A common stock, numerator (in Class A shares)	2,400	2,400
Ratio for converting shares of Class B common stock into shares of Class A common stock, denominator (in Class B shares)	1	1
Common stock, stated value per share	$ 70	$ 70
Common stock, authorized (in shares)	2,546	2,546
Common stock, issued (in shares)	2,546	2,546
Common stock, outstanding (in shares)	2,546	2,546