CONSOLIDATED STATEMENTS OF FINANCIAL POSITION (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Cash and cash equivalents	$ 199	$ 185
Other assets	406	441
Indemnity
Fixed maturities, amortized cost	479	535
Equity securities, cost	24	24
Trading securities, cost	23	23
Limited partnerships, cost	184	185
Cash and cash equivalents	28	11
Other assets	115	119
Treasury stock (in shares)	20,655,317	20,427,758
Exchange
Fixed maturities, amortized cost	6,939	6,829
Equity securities, cost	561	531
Trading securities, cost	2,014	2,021
Limited partnerships, cost	1,005	1,003
Cash and cash equivalents	171	174
Other assets	$ 291	$ 322
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)	68,294,400	68,289,600
Common stock, outstanding (in shares)	47,639,083	47,861,842
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)	2,544	2,546
Common stock, issued (in shares)	2,544	2,546
Common stock, outstanding (in shares)	2,544	2,546