Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 8,323	$ 8,222
Equity securities, cost	2,416	2,369
Land, building and equipment, accumulated depreciation	$ 398	$ 397
Common stock, par value	$ 2	$ 2
Common stock, authorized	500	500
Common stock, issued	197	197
Common stock, outstanding	197	197
Treasury stock, shares	34	34