Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Fixed maturities, amortized cost	$ 8,084	$ 7,888
Equity securities, cost	2,162	2,286
Land, building and equipment, accumulated depreciation	$ 376	$ 352
Common stock, par value	$ 2	$ 2
Common stock, authorized	500	500
Common stock, issued	196	196
Treasury stock, shares	34	34